An Accelerated Graphics Port (or AGP) is a special extension for graphics cards that support a 32-bit bus. An AGP video card is designed for a specific motherboard slot. Although these video cards are considered the last century, many motherboards come with AGP support. The AGP 8x video card had the AGP 3.0 specification, which could transfer up to eight blocks per clock cycle, thanks to which the bus bandwidth increased to 2 Gb / s.

Manufacturer Solutions

Each of the GPU manufacturers had the opportunity to improve the parameters of this interface. So, for example, ASRock solved the problem with the lack of a chipset on AGP video cards, developed the AGI 8x technology, which made it possible to support this expansion using a PCI slot. The famous company Gigabyte did the same, but with the participation of its own technology.

You may notice that some video cards do not have a shroud or cooler. In most cases, with older video cards on the PCB, only the heatsink cools the chip.

Radeon X 850 IceQ ll

The AGP ATI Radeon X850 XT IceQ ll Turbo 256mb video card opens the list of the best graphic processors. This video card has a 256-bit bus. According to the chip, the frequency is 520 megahertz, and according to the memory - 540 megahertz. Type of memory - GDDR 3, which is located on eight chips, on both sides of the PCB.

The exterior is a cooling from Arctic Cooling, where the built-in cooler in the video card is painted in an ultraviolet paint that glows in the dark. The copper base of the cooler fits snugly to the core and memory chips, where the plate heatsink is soldered. The casing contains a turbine through which air enters, and a bell designed to eject hot air from the system unit. The turbine speed is 2500-6000 rpm, which allows the video card to work almost silently.

GIGABYTE Radeon 9600 Pro AGP

At the time of the release of this AGP Radeon video card, its cost was 5740 rubles. With 128 megabytes of video memory, GDDR format, it had a core frequency of 400-600 megahertz. Also supports DirectX 9.0 and OpenGL 1.5. To display the image on the screen, DVI and VGA connectors were provided, and there is a TV-out video output for connecting to a TV.

Among the advantages of this AGP video card, users noted its durability. No deficiencies found.

PowerColor Radeon HD 3450 AGP

This card, carrying on board already 512 megabytes of GDDR2 memory, had support for the new DirectX version 10.1 and OpenGL 3.1. DVI and VGA video output connectors are also available, with a core refresh rate of 888 megahertz. The price of the ATI Radeon HD 3450 video card ranged from 3281 rubles to 4520 rubles.

The reviews note the advantage - the presence of an AGP interface that supports older models of motherboards. In addition, many games needed support for the updated DirectX.

Among the shortcomings in the reviews, there are many complaints that this video card requires additional power. Many users note that often the installation of native drivers incorrectly affects the operation of the video card.

GIGABYTE GeForce 6600 AGP

The first video card on the list from Nvidia manufacturers has a type of GDDR memory, 256 megabytes in size. The frequency of the video core is 400 megahertz. Among the video outputs there is an addition, in the form of a component connector, which is designed to output images to digital projectors. Standard support for DirectX 9.0 and OpenGL 1.5. The price of this video card AGP 8X, at the time of release, is 5740 rubles.

Positive user reviews indicate that the card is very quiet and powerful. Demanding games from 2006-2007 were played without problems.

The disadvantages of this GPU lie in the extra power, otherwise it will be impossible to play.

XFX GeForce 7950 GT AGP

This AGP 512mb video card has a 256-bit bus and GDDR 3 video memory. The frequency of the video core is 550 megahertz, and the memory frequency is 1200 megahertz. The card has two DVI connectors, one TV-out connector and a component video output. Supports DirectX version 9.0 and OpenGL 2.0. When published, it cost 12,300 rubles.

Many users still use this video card, noting high performance in its merits, despite the release date.

The disadvantage lies in poor cooling and rapid heating under heavy load.

MSI GeForce FX 5200 AGP

The GeForce FX 5200 is a great budget solution as it only costs 2064 rubles. 128 megabytes of video memory with GDDR format has a video core frequency of 250 megahertz, and a memory frequency of 400 megahertz. This video card has three different video output connectors and supports DirectX 9.0 with OpenGL 1.4.

Power - this advantage is often found among reviews of this video card. She is able to withstand many modern games without much effort. Users also note its durability and 128-bit bus.

The only disadvantage of users is the outdated graphics card design.

GIGABYTE GeForce 4MX 4000 AGP

Another AGP 8x video card with 128 megabytes of memory and GDDR format. The frequency of the video core is 275 megahertz, and the memory is 400 megahertz. This GPU has only two video outputs - VGA and TV-out. One of the few cards that supports DirectX 7 and OpenGL 1.3.

Among its advantages is good cooling, even when overclocked to 3000 gigahertz. Most optimized PC games will run smoothly with this card. Also, many praise the throughput of the 64-bit bus.

There are no disadvantages.

GIGABYTE GeForce 7600GS AGP

This GeForce AGP graphics card has 256 megabytes of 2nd generation GDDR memory. The core runs at up to 400 megahertz and the memory at 800 megahertz. It also has connectors for every taste, even component. Supports DirectX version 9, together with OpenGL 2.0. The price of this video card at the time of release is 8940 rubles.

The first advantage that users note is the affordable price. Most of the positive reviews contain information about low noise and high performance.

The disadvantage is the lack of support for the tenth version of DirectX. Demanding games can run at 10-20 frames per second.

Palit GeForce 4 MX 440 AGP

The first video card in the AGP list from the manufacturer Palit, which has 128 MB of GDDR memory and a 128-bit bus. It has only two video output connectors - VGA and TV-out. The core refresh rate is 275 megahertz, and the memory is updated at a frequency of up to 512 megahertz. Another graphics card that supports DirectX 7. Its price is only 1400 rubles.

Of the positive reviews, we can highlight the frequent mention that the video card is small and does not take up much space in the case. It does not heat up and does not make noise during operation.

There are a lot of disadvantages too. For example, the complete absence of shaders, even the simplest ones. Also, this card cannot be inserted into SLI. When working with it, many users complained about the high temperature of the video card.

Inno3D GeForce 7600 GT AGP

And here is the "monster" of its time, which has a 128-bit bus. With 256 megabytes of GDDR 3 format memory, the core frequency could reach 560 megahertz, and the memory was upgraded to 1400 megahertz. The video card had all available connectors for the ability to display an image on a screen or projector. Supports the ninth version of DirectX and OpenGL 2.0. The cost of this graphics card at the time of release was 4990 rubles.

A lot of positive reviews, where users agree that the main advantage of this video card is the support for the GDDR 3 memory format.

There are no shortcomings, as such, but several users found marriage. There was a breakdown in vertical stripes when starting the computer, which was not observed while working with other cards.

PowerColor Radeon HD 3650 AGP

The ATI Radeon HD 3650 completes the list of the best, which has as much as 512 megabytes of GDDR 2 video memory. The internal core operates at a frequency of 725 megahertz, and the memory shows a frequency of 1000 megahertz. This GPU has two DVI video outputs, one TV-out and one component, to work with projectors. ATI Radeon HD 3650 is capable of running DirectX 10 and OpenGL 3.1. The price at the time of release was 5500 rubles.

Competent cooling solution and high performance - these advantages characterize the video card. Also, many like the large, at that time, the amount of video memory.

The disadvantage lies in the high price, if you apply the price-quality ratio.

In conclusion, we can add that not all video cards had a connector for outdated boards - many had to use adapters. Despite such inconveniences, many players still successfully use older GPUs, as their performance and durability can make even modern video card representatives jealous.

With its interface part, the video card is inserted into the motherboard of your computer. In fact, this is a slot through which the computer and the video card exchange information. Since the motherboard usually has a slot of one type, it is important to buy a video card that will match it. For example, a PCI Express video card will not work in an AGP slot. They are not only physically incompatible, but also use different data transfer protocols.

The most important aspect of a graphics card interface is bandwidth. The term "bandwidth" refers to the amount of information that can pass through an interface in a given amount of time. The more bandwidth the interface gives, the faster the video card can work. At least in theory. But in practice, the interface does not mean as much as one might think.

ISA

ISA stands for Industry Standard Architecture.

Here, this interface is present only as a representative of a long history, since it is the oldest standard. Video cards with ISA interface have been outdated for a very, very long time. Today, even a motherboard with an ISA slot is very hard to find.

There were 8-bit and 16-bit versions of ISA cards. Only the last option used all contacts completely (see photo). EISA or Extended ISA cards made it possible to increase the bandwidth to a width of 32 bits, in addition, they supported bus mastering. But such cards were too expensive, so they gave way to other interfaces.

PCI

32-bit classic PCI bus. To this day, it is used for various expansion card standards.

PCI stands for Peripheral Components Interconnect. In the basic version, this is a 32-bit bus operating at 33 MHz and providing a throughput of 133 MB / s. The PCI interface replaced ISA and its VL (Vesa Local Bus) extension in the 1990s, providing higher bandwidth. PCI is the modern standard for most expansion cards, but video cards moved away from the PCI interface to the AGP standard (and later to PCI Express).

Some computers do not have AGP or PCI Express slots for graphics upgrades. The only possibility for them is the PCI interface, but video cards for it are rare, expensive, and their performance leaves much to be desired.

PCI-X

PCI-X stands for "Peripheral Component Interconnect - Extended", that is, we have a 64-bit bus with a bandwidth of up to 4266 MB / s, depending on the frequency. PCI-X (not to be confused with PCI Express!) is the first high-speed upgrade to the PCI Express bus, but it also comes with a number of features useful in the server space. The PCI-X bus is not very common in regular PCs, and PCI-X video cards are very rare. You can install a PCI-X card in a regular PCI slot if it supports the latest version of the standard (PCI 2.2 or higher), but is not compatible with the PCI Express PCI-X standard.

AGP

AGP interface: Accelerated Graphics Port.

AGP is a high bandwidth interface specifically designed for graphics cards. It is based on the PCI specification version 2.1. Unlike PCI, which is a common bus for several devices, the AGP interface is dedicated only to the video card. As a result, AGP provides numerous advantages over the PCI bus. For example, the ability to directly write or read to RAM, demultiplexing, simplifying data transfer protocols and increasing clock frequencies.

The AGP interface has gone through several versions, with the latest being AGP 8x at 2.1 GB/s, which is eight times faster than the original AGP standard at 266 MB/s (32 bits, 66 MHz). AGP on newer motherboards is giving way to PCI Express interface, but AGP 8x (and even AGP 4x) still provide enough bandwidth for modern video cards. All AGP 8x cards can work in both AGP 4x and AGP 8x slots.

Unlike ISA, PCI, and AGP, the PCI Express standard is serial, not parallel. Therefore, the number of contacts has significantly decreased. Unlike parallel buses, the required bandwidth is available to each device. While, for example, for PCI, the bandwidth is shared between the cards used.

PCI Express allows multiple single lanes to be combined to increase throughput. The PCI Express x1 slots are short and small, yet offer a total speed of 250 MB/s in both directions (to and from the device). PCI Express x16 (16 lanes) gives a throughput of 4 GB / s in one direction, or 8 GB / s in total. The smaller PCI Express slots (x8, x4, x1) are not used for graphics. It should be noted that a slot can mechanically correspond to x16 lines, but logically a smaller number of them can be connected to it. There are many motherboards that have two PCI Express x16 slots that can work in x8 mode, which allows you to install two video cards (SLI or CrossFire).

While the increase in throughput is a welcome improvement, the industry has run into another hurdle: power consumption. The AGP 3.0 interface (AGP 8x) is capable of supplying no more than 41.8 W (6 A on the 3.3 V line, 2 A on the 5 V line, 1 A on the 12 V = 41.8 W and an additional 1.24 W on the optional lines 3.3 V at 0.375 A). Therefore, video cards have got one 4-pin power socket (for example, ATi Radeon X850 XT PE) or even two (nVidia GeForce 6800 Ultra).

By adding 4-pin connectors, manufacturers were able to extend the life of the AGP interface, since the lines provide 6.5 A or 110.5 W (12 V + 5 V or 17 V at 6.5 A = 110.5 W). In general, the PCI Express interface has become a simpler solution, since it provides 75 watts through the x16 connector and an additional 75 watts through the 6-pin power socket, that is, 150 watts in total. PCI Express removed concerns about future bandwidth and power requirements.

"I would like to discuss the topic in order to once and for all deal with the question of what to drive the AGP on." - XSS

This article (hopefully not the last one) will discuss what platforms exist for benchmarking video cards with an interface AGP. If your task is to cut down more bolts on the well-known site ( how did you not hear it? Write, we will tell), then you are in the wrong place - you can't earn much on AGP. Taking the top-end processor at the moment, overclocking it in the air and overclocking the ten most popular video cards of past generations, you will get more trashballs in this way than by overclocking, perhaps, all AGP cards. Therefore, AGP benchmarking is a matter of personal interest, "old school", a tribute to memory, and everyone decides for himself what else.

The main problem facing 3D benchmarking is processor dependence. It is she who does not give full return on video overclocking, and sometimes allows you to bypass overclocked cards on default. Although it seems that AGP cards are so weak that their processor dependence is minimal, this is not so. Previously, the main battle in the AGP camp was between socket A And socket 478.

We will consider what opportunities for benchmarking AGP video cards have appeared almost 10 years after the publication of the above article, where, by the way, the penultimate generation was raced AGP- video cards.

Intel platform

Proven Solutions

There are practically no options for crafts from ASRock. Motherboards are widely used and support all LGA775 processors (namely - including Penryn). ASRock ConRoe865PE north bridge - Intel 865PE. Declared support for all Core2 and Core2 Quad on Kentsfield. DDR1. With overclocking in the BIOS it's sad. The processor supply voltage is changed by a simple voltmod. Discussion on overclockers.ru ASRock 4CoreDual-SATA2

Other Solutions

Chipset Intel 865G. Officially does not hold quads. The most maximum X6800. There is a modified BIOS for the board, which significantly expands its capabilities.

north bridge - VIA P4M800 Pro. The latest BIOS is from mid 2007, so the board probably doesn't support Penryn. Thus, its limit is X6800. Gigabyte GA-8I865GME-775-RH

north bridge - Intel 865G. Revisions 2.0 , 3.9 And 6.6 support Core2 65nm, latest revision 6.6 - quads up to QX6800(There is no mention of QX6850 support, although in theory it should be on a lowered bus). The latest BIOS is dated 2007, i.e. there is definitely no support for Penryn. Visual differences between revisions of the board can be studied in the following picture:

Gigabyte GA-VM800PMC

north bridge - VIA P4M800 Pro. Supports Pentium Dual-core E2xxx and Core2 Duo E4xxx only. Even E6xxx is not officially supported, not to mention quads and Penryn. In order of working nonsense, it is also worth mentioning the following boards:

These revisions support Pentium Dual-core E2200/2220 and Core2 Duo E4300. I won’t say more good things about them, and I can’t.

It should be recalled that the chipset must operate at maximum frequency and independently of memory (be able to change memory dividers). On the processor, in most cases, the voltage must be increased, which is possible only with modifications to motherboards. The chipset voltmod is also recommended in some cases. With processors, as elsewhere, there are two options. Bus overclocking and free multiplier.

Tire acceleration. Let's take 300 MHz on the bus as a starting point, which is quite realistic for most mothers on both Intel and VIA. To achieve the maximum effect, you need a low nominal bus, a high multiplier and as large a cache as possible. I draw special attention to the fact that we are talking about the theoretical limit of overclocking on the bus, based on the limit of 300 MHz for the motherboard. Compare the data with objective reality - that on the E5800 you will not reach bus 300, since the frequency of 4800 MHz in air for the E5xxx is unattainable. Closer to reality - about 4GHz, for E4xxx - 3.7-3.9GHz. For the E8400, it is really possible to go above the named frequency, since 300 MHz is taken from the 99% guarantee of operation, but in fact the boards can go up to 320 MHz, and sometimes even higher. Ideally, test your processors on decent motherboards first for overclocking potential, voltage boost, FSB wall, etc. 2 cores, 2 caches, 200 bus The easiest and most budget option.

• Core 2 Duo E4600 or Core 2 Duo E4700

2 meter cache bus 200 (800) MHz. Multiplier 12/13. With overclocking to 300 on the bus, the limiting frequency 3600/3900 MHz.

• Pentium Dual-Core E5700 or Pentium Dual-Core E5800

All the same dull 2 ​​meters of cache, the same bus, a smaller technical process, but higher multipliers - 15/16 and better performance. Limit frequency 4500/4800 MHz. 2 cores, 3 caches, 266 buses

• Core 2 Duo E7500 or Core 2 Duo E7600

Multiplier 11/11.5. With acceleration, respectively, 3300/3450 MHz. And it is not known how the mother with a fractional multiplier will behave in the case of the E7600. 2 cores, 6 caches, 333 buses

A multiplier of 10, which with the discussed bus frequency gives 3000 MHz. Possessing a powerful cache of 6 meters, it can overtake all the above-described processors in 3dmarks, if a particular card in the test does not rest on processor performance. 4 cores, 8 caches, 266 buses

Probably the ideal option from cheap quads, if you choose only from Intel. Accurately supported by most mothers (not officially supported by 775Dual-VSTA and P5PE-VM). Limit frequency 3000 MHz. 8 meters of cache and 4 cores for AGP is quite cool in core-dependent brands (3DMark06). Overclocking with multiplier

Fierce Intel exotics, rather an exception to the rule. free multiplier. The default is 11, bus 266. Unfortunately, the cache is only 2 meters. In air, the processor is completely similar to the E5700/5800, since the ultra-high multipliers of the E6500K are unattainable due to the too high final frequency (the E6500K runs like the E5200-5800, i.e. 4.5-4.7 GHz in the air cannot, like the E8400-8600 ) Of the six pieces of XE processors under 775, only three and a half are interesting.

• QX9770 is a top processor. Even the nominal bus is unattainable on the motherboards under discussion, so it will work on a smaller bus. In fact, for us, he is a Wolfdale with a free multiplier, from 4 cores to sense about zero.

• QX9650 - the same, but cheaper. Therefore, if you do not feel sorry for the money, it is recommended to purchase, as the best for AGP tests, at least on Intel.

• X6800 The only one in the line with two cores. Bus 266, but only 4 meters of cache are alarming. Surprisingly, at the moment it's cheaper on eBay than the more dismal E6500K mentioned above.

• QX6700 8 caches, 266 bus.

• If you have enough money and don't feel sorry for it - QX9770/9650, we get Wolfdale with six meters of cash with a free multiplier
• If there is less money, we take the E5300-5800 (with the younger ones you will have to squeeze the bus a little more to reach the limit of the stone), it is recommended to take the E8400/8600 in conjunction for an increase in cases that are undemanding to CPU power
• The same, but with powerful cryogenic cooling and the desire not to be like everyone else - instead of the E5800 we are looking for the E6500K
• The simplest competitive option - E4600/4700

AMD platform

Classic scheme - southbridge NVIDIA nForce3 250, while DDR2 memory is divorced and supported by Phenom II. The board does not support unlocking cores, ie. if you are going to run 3DMark06 on 4 cores, you need Phenom II X4.

A more perverted scheme using a bundle as a chipset ULi(purchased by NVIDIA) M1695 + nForce3 250, and therefore has PCI-E and AGP ports, otherwise identical to AM2NF3. Also does not support unlocking cores. Processors

• AMD Phenom II X2 555-570 Black Edition
• AMD Phenom II X4 955-980 Black Edition

It is advisable to look for C3 stepping processors, due to their higher overclocking potential.

Beginning of the era of PCI-Express

The time has come when even the bandwidth of the AGP 8x interface is no longer enough, and there is a need to replace the old PCI. Then it appeared 3GIO(3rd generation I / O - third generation I / O system) codenamed Araphoe. What is now known as PCI Express. When the standard was adopted, Intel announced that the next round of evolution (in the form of i915P/925X chipsets) would be accompanied by a complete infrastructure change - socket 478 to socket T (AKA LGA775), DDR1 to DDR2, AGP to PCI-Express. GPU manufacturers with AGP chips are quickly updating their solutions - ATI releases Radeon X-series with native PCI-E support, NVIDIA creates a two-way HSI adapter bridge, allowing manufacturers to adapt AGP chips to the PCI-Express standard, and even XGI creates your own bridge. The Rialto bridge was also created by ATI, but it was used only to create AGP versions of PCI-E video cards.

XGI XG47

Radeon 3850 AGP

NVIDIA stood out separately - the NV40 chip, released under the name Geforce 6800GT/Ultra, had an AGP interface and hit just at the moment when PCI-Express appeared. Instead of using the same solution as in Geforce PCX and soldering the HSI bridge on the board, NVIDIA solders the HSI directly on the GPU substrate! The solution was called NV45, but did not last long, giving way to NV41 and NV42, which had native support for PCI-E.
During this transitional time, as is usually the case, solutions began to appear that sought to help those who did not fall into the evolutionary round imposed by Intel - i.e. those who had a powerful AGP video card and wanted to upgrade an old AGP system, or vice versa, had an AGP platform that was not inferior in performance to the new LGA775, but wanted to upgrade their video card. Versions of cards with two interfaces - both AGP and PCI-Express - were created and demonstrated.

HIS X1600 Pro

Adapters

Since the bridge HSI works in both directions, then the idea of ​​​​an adapter, one might say, was in the air. And was embodied by the company Albatron, which released the adapter ( A GP To P CI-E).

Adapter Albatron ATOP

Albatron ATOP adapter system in action

It would seem to be an ideal option for testing AGP cards in PCI-E motherboards. But the limitations of its operation made it almost unusable:

1. Very limited list of supported cards (Geforce 2, which is the closest relative of the supported Geforce4 MX, did not launch. Nor did any ATI card)
2. Because of the jumpers, which apparently set the Dev_ID of the strap, the card is determined by the drivers and GPU-Z as corresponding to PCX, i.e. having a PCI-E interface, not AGP.

AGP 2x to PCI66 This adapter was not the only one made, but one of the latest options is the trevormaco version called , where a simple electrical AGP adapter to the PCI bus is made. In mode PCI66, the AGP connector will operate in the AGP1x(i.e. without multiplexing, but on a 66MHz bus). It was developed for Voodoo 6000 video cards, therefore it has an appropriate price tag and an AGP 2x standard connector. Because PCI, only 3.3V cards are supported.

AGP2PCI adapter

System based on AGP2PCI adapter and 3dfx Voodoo 5500 AGP

Platform for AGP 2x cards, conclusion

If AGPs as a whole have a small pool of points to earn, then AGP 2x is a completely thankless task in this sense. In addition to exotics with an AGP2PCI adapter, there are also platforms for working with such cards. Due to the fact that motherboards with AGP 8x support do not support 3.3V cards, to test old AGP 2x cards, you have to use motherboards with AGP universal connector, which only support .

Boards based on the following chipsets are suitable for the Intel platform:

• SiS 645
• VIA P4X266E

For AMD, the top chipset is VIA KT333, which is used in most categories, especially since many socket A processors have a free multiplier.

Cards with an AGP 2x interface have a slot in a different place from the AGP 8x slot, so they won't physically fit into the cards mentioned above. But they will fit into universal AGP 4x boards. There are also 1.5V AGP 4x boards, which have a slot in the same place as AGP 8x boards, and the same compatibility restrictions (ie, they do not accept 3.3V AGP 2x).

AGP 2x connector

universal (without keys) AGP 4x connector; omnivorous

AGP 4x 1.5V socket or AGP 8x socket; does not accept AGP 2x cards

Conclusion

I hope this article has helped answer your questions about AGP card benching, discovered something new or refreshed the forgotten. I want to thank you first of all XSS, who at one time raised this issue and began work on streamlining the existing knowledge.

I also express my gratitude to the team members (I think you yourself will understand who): Always More Digital, Hardware Hackers, Team MXS website, Team Russia, XtremeLabs.org and just free overclockers, if I forgot someone. I hope this will be the first sign of such articles.

Recently, a huge number of questions on the AGP standard have appeared in conferences, and, in particular, on the compatibility of video cards and motherboards that support different versions of this standard. This article is an attempt to talk about this interface and answer many questions, in particular, about the compatibility of old motherboards with new video cards.

So, AGP backbone interface. Calling it a bus is not entirely correct it was not originally designed for several expansion slots, and although the AGP 3.0 specification mentions the possibility of such configurations, nothing like this appeared in the hardware. This interface was developed by Intel for connecting video cards. When it was introduced, grandiose plans were made it was supposed to almost completely abandon the local video memory, and use the system memory instead. The first step in this direction was the Intel 740 video card, which installed a relatively small amount of memory used for the framebuffer and Z-buffer, and all textures were stored only in system memory. But the path turned out to be a dead end the relatively slow system memory could not compete with the wide and fast memory buses of video cards the rejection of expansion modules made it possible to implement 128- and 256-bit access, and significantly softer requirements for the fault tolerance of individual memory cells made it possible to increase the frequency even on those the same microcircuits. The thing is that changing the contents of a single cell of video memory can not greatly affect the picture it is almost impossible to notice a point that has changed color on a single frame, while in the case of system memory such a failure will have much more sad consequences. Moreover, with such requirements for fault tolerance, it is possible to increase the frequencies very much on the RADEON VE card from PowerMagic that I had at one time, Hynix HY5DU281622AT-K chips were installed. As you can easily understand from the markings, these DDR SDRAM chips were intended for use as system memory with a maximum frequency of 133MHz (266MHz DDR). As video memory, they worked at a nominal frequency of 166MHz (333MHz DDR), moreover, they did not show noticeable artifacts when overclocked to 210MHz (420MHz DDR). So modern cards store textures in their own memory, using the capabilities of AGP only in case of its shortage, and the Intel 740 remained the only accelerator of its kind, later becoming the basis of the I752 graphics core built into many chipsets from Intel in this application, its features fell just by the way.

1. AGP 1.0: How it was…

The AGP 1.0 interface was based on the PCI 2.1 bus, or rather, its variant PCI 32/66 32-bit bus with a frequency of 66MHz. The AGP 3.0 standard provides for an extension of the bit depth to 64 bits while maintaining backward compatibility, but such configurations have not yet been implemented. Electrically (but not in terms of slot and wiring), AGP 1.0 remained backward compatible with PCI, but received some extensions:

1. Request queue. On AGP, unlike PCI, it is not at all necessary to wait for the end of the current transfer to transfer the next address - you can make several read (write) requests at once, and then sequentially read (transmit) the data.
2. Partial demultiplexing of address and data buses. The implementation is very original in addition to the standard 32-bit multiplexed bus (AD) there is an 8-bit side address bus (SBA). The algorithm is as follows: when the request queue is empty, the first few address transfers are performed as standard, via the multiplexed AD bus, and after the requested data goes through it, the next addresses will be transferred to the queue via the SBA bus.
3. DDR mode for data lines. Already in the AGP 1.0 standard, a 2x transmission mode was implemented on the AD and SBA lines with double the frequency, along the rising and falling sides of the clock signal. Contrary to popular misconception, motherboards that support only 1x mode simply do not exist the first AGP chipset, the Intel 440LX, had already implemented 2x mode.

   This variant of AGP quickly became a common standard, with VIA, SIS and ALi releasing their own AGP chipsets.

2. AGP 2.0: …and miracles begin…

Quite quickly, the development of system memory led to the fact that its bandwidth exceeded the bandwidth of AGP 1.0 even in 2x mode. Naturally, a new standard, AGP 2.0, was developed. And this is where the miracles began... In addition to minor improvements in the Bus Master mode, which remained from PCI, there was one single, but global specification change - to implement QDR transfers (4 transfers per clock), the signal levels of the interface were reduced to 1.5V instead of 3.3V in AGP 1.0. Due to the fact that at such frequencies the capacitance of the conductors begins to play a significant value, lowering the level of logical "1" can reduce the consumption of output stages and increase speed and stability. Contrary to common misconceptions, the voltage of the lines that supply power to the chip and memory (or their stabilizers) has not changed all 3 lines, VDD 3.3, VDD 5 and VDD 12, remained in the connector. From 3.3V to 1.5V, only the VDDQ supply voltage for the output stages of the chip has changed. Few people know, but this decision is rooted in the PCI specification initially, this bus had a logical “1” level of 5.0V, and in the PCI 2.1 specification, to implement the 66MHz frequency, it was reduced to 3.3V. There were no problems, firstly, because the PCI 32/66 and 64/66 variants have not yet received wide distribution, being present only in server solutions, and secondly, due to the fact that the bus signal levels are uniquely set PCI slot keys:

Top 66MHz slot, bottom 33MHz.

To ensure compatibility with AGP 1.0 of new motherboards and video cards, the following steps have been taken:

As long as the chipsets supported AGP 1.0 modes, everything was fine. But after the release of Intel's 845xx series chipsets, which did not support 3.3V signal levels, it turned out that not everything was as smooth as it seemed ...

The first and grossest mistake of the manufacturers was the installation of universal slots on these boards, instead of the slots with the “1.5V Only” key required by the specification. It would seem that it's okay, VDDQ is still 1.5V, a 1.0 standard card simply won't start, but as it turned out, standard 1.0 cards, even with VDDQ 1.5V, still output 3.3V to the chipset inputs designed for 1.5V. Naturally, the unfortunate north bridge could not stand such mockery, and burned completely, after which the board could be safely thrown away very few companies had equipment for soldering BGA and spare bridges. Fortunately, the lesson was learned from this quickly enough, and the keys to the slots appeared. But the problems have not disappeared. As it turned out, some cards, despite the fact that they had a universal connector, were either partially compatible with AGP 4x or not compatible at all. In the best case, the cards simply did not start or were unstable, at worst, they stupidly turned on three-volt levels, of course, with a subsequent fatal outcome for the north bridge. There were also, for example, cards on which the signal levels were set by a jumper. Naturally, by default it was in the "3.3V" position. Fortunately, the TYPEDET# signal on such cards, as a rule, gives correct information, so some manufacturers, for example, ASUStek, have made a protection scheme based on this principle if the TYPEDET# level is high, the board will not start. You can find out which cards can be bet on these chipsets and which ones can't from the table below. To be installed on these chipsets (as well as on all subsequent chipsets with AGP 8x support), the card must support AGP 2.0:

Table of support for AGP standards for video cards:

3. AGP 3.0 …more and more weird…

So, it's time for AGP 2.0 to retire as well - its bandwidth is no longer enough. In the new 3.0 standard, the level of logical "1" was once again changed reduced to 0.8V for 8x mode. The reference frequency of the interface has not changed, just the ODR mode was introduced transmission over the AD and SBA lines with a frequency 8 times higher than the reference frequency. Naturally, we added two new lines GC_AGP8X_DET# and MB_AGP8X_DET# , respectively, defining AGP 3.0 support for the video card and motherboard. The connector remains the same AGP 4X / 1.5V Only (oh, in vain, they would not have stepped on the same rake again if they refused to support 1.5V signal levels), protection is provided by the GC_AGP8X_DET # line at its high level, the motherboard supports only AGP 8x should not start. And, of course, miracles with signal levels continued... According to the Intel standard, both the card and the motherboard, if they support AGP 8x, should not support modes with levels of 3.3V (this does not mean at all that there is no support for 1x mode! Back in the AGP 2.0 standard there were 1x/1.5V and 2x/1.5V modes defined). In practice, although motherboards do fulfill this recommendation, everything is far from being the case with video cards. Almost all modern video cards with AGP 8x support also support AGP 1.0 motherboards (the only exception is RADEON 9600). Another thing is that signal level compatibility is a necessary, not a sufficient condition for performance. For example, old power supplies of something like RADEON 9700 simply, as a rule, can't stand it. But there are examples of working configurations, so if you want, any card, even the RADEON 9800 PRO, can be installed on the Intel 440BX, for example. But does it make sense?

AGP standards support table for chipsets:

These are the very first chipsets with AGP support. The possibility of stable operation of new cards depends entirely on specific motherboards. Naturally, you shouldn't expect much from ACORP, while ASUSTEK, for example, can also run the RADEON 9700...

The first non-Intel chipset with AGP. Strange as it may seem, I didn't have any serious hardware problems (apart from specific implementations of AGP on some motherboards, but that's not VIA's fault). It is highly recommended to update the BIOS before installing new cards.

For early boards, it may be necessary to manually select the AGP Driving Value for stable operation of the 4x mode.

Since the editor does not approve of swear words, I will not say anything about the implementation of AGP in this chipset and motherboards based on it. Types of working video cards are recognized only by selection ...

Well, to the heap:

Table of all AGP modes:

As can be seen from this table, in AGP 2.0 and 3.0, the 1x and 2x modes were not abandoned, but simply transferred to 1.5V signal levels. So don't be surprised to see the "1x" option in the AGP mode settings on newer boards. 4. And now about what follows from this, and how to put it all into practice

1. Compatibility of new motherboards and old cards can be determined from the tables above. In disputable cases, it is recommended to install the card on a motherboard with a universal 1.0/2.0 slot, and control the activation of the AGP 4x mode using RivaTuner or PowerStrip. If the card works in this mode, it can be safely installed on new boards.
2. It is impossible to burn a new video card by installing it into an old motherboard. Currently the only card without AGP 1.0 support is RADEON 9600/PRO, but it doesn't threaten it either, because it won't physically fit into old boards.
3. Despite this, the stability of the configurations "old board + new video card" is not guaranteed.

This section contains most of the problems that may arise when installing new video cards on old motherboards:

Insufficient power supply.
Problem:
The power of the power supply is insufficient.
Symptoms:
Departure of supply voltages from admissible limits.
Starting the system only after pressing reset.
High level of power interference, and, as a result, arbitrary malfunctions (hard to determine).
Solution:
Replace BP.

The motherboard has a stabilizer on the VDD3.3 line(Immediately warning possible questions on most boards, the supply voltages to the AGP are supplied directly from the power connector of the motherboard. What is called VAGP in the BIOS is just VDDQ, and you should not increase it).
Problem:
Due to a low-power stabilizer on the VDD3.3 line, the video card does not have enough power.
Solution:
For AT board installation of a more powerful stabilizer (difficult).
For ATX boards powering the video card directly from the PSU, as a rule, by disconnecting the stabilizer and soldering the conductor from the power connector. On some motherboards, the stabilizer is disabled by jumpers.

Invalid VREFGC level.
Problem:
The VREFGC voltage supplied by the 2.0 standard card to pins A66 and B66 is shorted to ground by the 1.0 standard board. In the 1.0 standard, these pins are reserved. Why the reserved contacts had to be grounded is a mystery hidden in the darkness of the night. This is how it was done, for example, on Chaintech 6BTM
Symptoms:
The system does not start.
Solution:
Isolate the last two pins in the slot.

Low power VDDQ stabilizer.
Problem:
Bus transfer instability due to low power VDDQ regulator. In especially neglected cases the use of a common VDDQ stabilizer for AGP and RAM. For information: according to the AGP standard, the maximum permitted current of the VDDQ line is 8 amperes.
Symptoms:
System instability, especially in 3D games. For the general VDDQ AGP and memory stabilizer instability appears when installing several memory modules or modules with a large number of chips together with a new card.
Solution:
Install a more powerful stabilizer. For the second case decouple VDDQ memory and AGP. Both that, and another it is difficult, it is easier to replace a payment.

High Frequency AGP
Problem:
On the Intel 440BX chipset, when using processors with a 133MHz bus, the AGP frequency is 89MHz instead of the standard 66.
Symptoms:
System instability, especially in 3D games. Sometimes the system does not start at all.
Solution:
Set mode 1x. In the absence of a positive result DECREASE the voltages VDDQ and VREF, but not more than 5% of the nominal value (to 3.135V and 1.5675V minimum). Please note that VREF=VDDQ/2, and the permissible deviation is not more than 2%. This is especially critical for ABIT and ASUStek boards, in which VDDQ (and, accordingly, VREF) can be overestimated by default, which in this case does not add stability at all ... The question is often asked what about a card with 4x or 8x support? 89MHz is not capable of digesting? The answer is simple firstly, in normal operation, the frequency of all lines, except for AD and SBA, remained 66MHz, even in the 3.0 standard. Secondly, although the lines on AD and SBA in 4x mode and above operate at a frequency exceeding 89MHz (or 178 for 2x mode), they work at other signal levels ...

The abbreviation AGP is either familiar to you, or you don't like to play on the computer. This is the name of a popular type of system bus, which has a special connector format for connecting expansion cards. There are many expansion cards designed for this 32-bit bus, and almost all of them belong to the category of graphics accelerators. Although at present, since 2010, video cards for this bus have practically not been produced, since it has lost the palm, nevertheless, there are many computers that have graphics accelerators designed for the AGP bus.

During the entire existence of the system bus of a personal computer, several of its various standards have been developed. However, only a few of these buses were designed specifically for connecting video cards. The AGP bus is one example of such a bus.

Perhaps readers will be interested to know what this abbreviation stands for. It stands for Accelerated Graphic Port. The AGP bus was developed by Intel in 1996 as an enhancement to the PCI bus, and was first used in Intel chipsets designed for Pentium and Pentium 2 processors. Windows family operating systems introduced bus support starting with Windows 95 OSR2 and Windows NT 4.0 SP3.

The main idea in developing the bus was not only to increase the efficiency of the computer's video system, but also to reduce its cost. This was supposed to be achieved by reducing the amount of RAM on the card, since the Accelerated Graphic Port standard assumed improved capabilities compared to PCI for using the main RAM of a computer.

During the existence of the tire, several of its specifications were released, the latest of which was the 3.0 specification. In addition, several bus speed standards have been developed, ranging from 1x to 8x.

As computer hardware has developed since the mid-2000s, however, it has become obvious that the AGP bus does not meet the new requirements for graphics accelerators. Therefore, several extensions to the standard were created, such as the 64-bit Accelerated Graphic Port bus or a variant of the bus called the Accelerated Graphic Port Pro. In addition, a number of unofficial bus extensions have been created by some motherboard developers, but they are not widely used.

Characteristics and difference from PCI

Before the advent of the Accelerated Graphic Port bus, the vast majority of graphics accelerators used a PCI slot. Unlike PCI, the new bus had twice the clock speed (66 MHz), as well as twice the data transfer rate (533 MB / s). Although initially it had the same supply voltage as PCI - 3.3 V, later, in specifications 2.0 and 3.0, it was reduced to 1.5 and 0.8 V, respectively. Also, unlike PCI, the bus supported direct DMA memory access and separation of data processing requests. The bus was designed to manage the AGP controller located in the chipset of the motherboard.

The bus characteristics of the various versions are shown in the following table:

A standard AGP slot has 132 pins (66 on each side). In general, their location is similar to the PCI bus pins, but there are a few additional signals. At the same time, the connector may have several options that differ in operating voltage. The 1.5 V connector, like the 3.3 V connector, has a special protrusion that prevents the insertion of a board of the wrong standard. In addition, there is a universal connector that allows you to insert video cards of all types into it. There are also video cards that can be inserted into any type of slot.

However, it should be borne in mind that there are motherboards that use a connector designed only for a certain voltage value, and at the same time are not equipped with keys that exclude incorrect connection. Therefore, when installing video cards into the connector, you should pay attention at the moment, as well as study the instructions for the motherboard and video card and compare their characteristics, since connecting a video card to the connector with the wrong voltage threatens to damage both the card and the connector itself.

The connector for cards that support the Accelerated Graphic Port Pro standard also has two options for different voltages - 1.5 V and 3.3 V. Regular standard cards can be inserted into the Pro type slot, but the reverse operation cannot be performed.

Configuring the bus in the BIOS

Perhaps many readers are interested in such questions as how to enable AGP and how to configure AGP. For this purpose, the easiest way is to turn to the BIOS Setup tools. As such, the Accelerated Graphic Port bus is not enabled in the BIOS, it is activated by default. But in the BIOS you can find a lot of options designed to configure it. For example, with the help you can enable the fast recording mode for the video card. In this mode, the video card receives data directly from the CPU, bypassing the system RAM as an intermediate storage location. Using the same, you can set the size of the RAM that will be used by the video card with this interface. You can read more about setting up some parameters of the bus operation on our website in the section on BIOS options (“Chipset Settings”).

Conclusion

Although now in most motherboards the AGP slot has given way to slots of such a high-performance bus as PCI Express, nevertheless, the introduction of the Accelerated Graphic Port bus turned out to be a real breakthrough in the world of graphic video cards at one time. In addition, graphics cards of this format can still be found in many working computers.