by Alexey Stepin , Yaroslav Lyssenko, Anton Shilov
09/11/2007 | 10:13 AM
With all of their technical and usability-related shortcomings, multi-processor graphics solutions were successful in finding a niche of the discrete graphics hardware market to settle in at the time of Nvidia’s GeForce 7 and ATI’s Radeon X1000 architectures.
According to the statistical data gathered by Valve, multi-GPU technologies were utilized by about 1.5% of all gamers at the beginning of this year. This seems to be a realistic number. There are not too many people who stand no compromises between performance and image quality and want to have the maximum gaming speed regardless of how much it may cost. It is such devoted gamers that become the end-users of high-performance multi-GPU systems consisting of two ultra-fast graphics cards and an appropriate mainboard.
Trying to cater to this user audience, Nvidia even launched the world’s first gaming system with four GPUs called Quad SLI but the early version of this technology proved to be unsuccessful (for details see our article called Quadtet: Nvidia GeForce 7900 Quad SLI Performance Unveiled). The Quad SLI system didn’t deliver the performance expected from it and had a number of compatibility and image quality issues. Even more importantly, it couldn’t beat the opposing CrossFire tandem made out of two ATI Radeon X1950 XTX cards (for details see our article called Second Round for Nvidia Quad SLI: Technology Matured?).
Nvidia in fact abandoned its Quad SLI solution after the release of the new-generation GeForce 8 GPU series whereas multi-GPU tandems could not be popular because a single top-end graphics card would be faster than two mainstream cards joined together and also ensured a problem-free and fast operation in each and every game.
We tested the fastest available multi-GPU systems (using both Nvidia SLI and ATI CrossFire technologies) on our site before but the situation in this sector is different today than it was a year ago. The leading developers of discrete graphics solutions for the PC, AMD and Nvidia, have both released new-generation graphics processors, Radeon HD 2000 and GeForce 8, respectively. Another important factor is that Microsoft is actively promoting its new operating system Windows Vista as the main OS for gaming platforms, especially as the new version of the DirectX API exists for this OS only. We have already benchmarked the fastest available single-card solutions from both GPU developers in Windows Vista, now it’s time to check out the multi-GPU solutions as well.
As you know, Nvidia currently holds the title of the maker of the world’s fastest gaming graphics card and AMD has nothing to beat it with. The ordinary ATI Radeon HD 2900 XT, priced at $399, is a rival to the GeForce 8800 GTS 640MB. Having a high potential, this card is still no match to the GeForce 8800 GTX, let alone the GeForce 8800 Ultra. This lagging behind does no good to the already precarious position of AMD’s graphics department. The former ATI Technologies has to find a quick and ready answer to Nvidia’s aggressive policy.
Long before the writing of this review there emerged rumors about a Radeon HD 2900 XTX, a card that would make a worthy opponent to Nvidia’s GeForce 8800 GTX. The “long” version of Radeon HD 2900 for system integrators was being alluded to and various technical characteristics were being quoted, but different sources agreed on one point – the new card would certainly have 1 gigabyte of GDDR4 memory on board.
In late May, Sapphire Technology, a major partner of ATI’s, quietly adds a Radeon HD 2900 XTX into the list of graphics cards being supplied to the market. According to the list, the new card is indeed equipped with 1024 megabytes of GDDR4 memory clocked at 1025 (2050) MHz while the graphics core frequency remains the same at 742MHz. There is no official announcement from AMD while Sapphire refuses to comment upon the situation.
Later on, the Canada-based Extreme PC shop begins to accept pre-orders for Radeon HD 2900 XT 1GB at a price of somewhat higher than $600 but with GPU and memory frequencies of 825MHz and 1050 (2100) MHz, respectively. AMD was still keeping quiet, but it was clear the new Radeon HD 2900 had been already put on production lines and there would be no problems with the availability of the card. This was confirmed by the major memory maker Samsung who was supplying GDDR4 chips for the AMD Radeon HD 2000 series.
We’ve carried out a small investigation to find the following: AMD’s graphics department is not planning to announce the new Radeon HD 2900 with 1GB of GDDR4 memory officially. The responsibility for producing such cards lies with ATI’s partners in graphics card production such as Sapphire Technology, Diamond Multimedia, etc. If this announcement ever takes place, however, it will be only about the version with a graphics core frequency of 742MHz. We guess the company doesn’t want to spend its resources on culling chips capable of operating at increased frequencies. It is a rather laborious task that does not guarantee an increase in AMD’s market share.
As opposed to Nvidia who officially released its GeForce 8800 Ultra into retail networks, the overclocked versions of Radeon HD 2900 XT 1GB will be not only produced by ATI’s partners but also supplied mainly to system integrators. This is true for the Diamond Viper Radeon HD 2900 XT 1GB, for example. The clock rates of such cards may vary.
We have also found out the final specs of the non-overclocked Radeon HD 2900 XT 1GB: its graphics core frequency is indeed 742MHz but its memory frequency is lower than expected, 1000 (2000) MHz. Anyway, this ensures a record-breaking memory bandwidth of 128GB/s.
Thus, the AMD Radeon HD 2900 series looks as follows today:
As we have written above, the latest model is an initiative of ATI/AMD’s partners in graphics card production and will not have an official status. It will be mainly supplied to system integrators although some online shops offer such cards for about $610.
The difference in performance between the Radeon HD 2900 XT and the Radeon HD 2600 XT is very big, leaving not one, but several empty product niches. Clearly, even dual-processor RV630-based solutions can’t fill in this vacuum. However, there is yet no sign of AMD’s planning to release R600-based products with lower performance than the Radeon HD 2900 XT 512MB provides.
So, the Radeon HD 2900 XT 1GB exists for real. But differing from its junior brother in the amount and type of graphics memory only, this graphics card can hardly win absolute supremacy among single-card solutions. We don’t expect a record-breaking performance from the version with a 742MHz core frequency at least, yet we’ll check this out soon in the Tests section. A higher performance can be expected from a Radeon HD 2900 XT 1GB that comes with an increased graphics core frequency, though.
As a matter of fact, AMD pins its hopes of beating the GeForce 8800 Ultra on a tandem made out of two ordinary Radeon HD 2900 XT working in CrossFire mode. At an official price of $399, a pair of such cards can prove to be as fast as the Nvidia GeForce 8800 Ultra and even cheaper for the end-user. The success will depend on the implementation of CrossFire technology in AMD’s new GPUs and drivers. In this review we’ll try to find out if the multi-GPU solution of the former ATI looks competitive in this struggle.
Diamond Multimedia has a rich history, one that not many other graphics card makers can boast of. Back at the times of the ISA bus, when the PCI interface was only beginning to conquer the x86 world, Diamond Multimedia was already producing graphics cards based on chipsets from Tseng Labs and Cirrus Logic. Later on, the company earned a name for itself releasing the Diamond Stealth graphics card series. Early models were based on the then widespread 2D chips developed by S3 Graphics, but then 3D accelerators, based on S3 ViRGE and Rendition Verite processors, were added to the Stealth series as well.
Of course, those products cannot be regarded as full-featured 3D accelerators by today’s standards. Nvidia’s first solution, also employed by Diamond in its products, was not such, either. The NV1 processor was installed on a multifunctional card that combined a 2D/3D accelerator and an audio processor with support for wavetable-based MIDI synthesis, but that product did not really take off due to the lack of support for polygon-based rendering. The chip used quadratic texture maps instead of polygons whereas Direct3D, which uses polygons as the main primitive, was already becoming the number one standard in the world of PC graphics.
So, it was the release of the Monster3D card, based on the revolutionary 3dfx Voodoo Graphics chipset, that proved the real breakthrough. The name of Diamond Monster 3D became a legend among gamers whereas the audio card series Monster Sound, based on Aureal technologies, took its place among high-end gaming audio solutions next to Creative’s Sound Blaster Live!.
In 1999 S3 Graphics announced its purchase of Diamond Multimedia which was the beginning of the decline of the world-famous Diamond brand. S3 wasn’t much of a success. Its solutions were beset with problems. We can recall the inoperable T&L unit in the Savage 2000 chip which, ironically enough, was to become the world’s first GPU with support for hardware transformation and lighting. S3 Graphics eventually became part of VIA Technologies while the Diamond brand remained the property of SonicBlue, a company that was to produce multimedia products like MP3 players, but not graphics cards. July 2000 S3 announced that the Diamond Multimedia department was closed and the once-famous name was forgotten after a while.
The restructured company emerged on the market again in 2003. The rejuvenated Diamond Multimedia announced the return of the legendary brands Viper and Stealth and also took a neutral stance towards the GPU developers, without giving preference to any of them. One of the new Diamond cards made it into our test labs in 2004 but it was an entry-level solution on the already outdated ATI RV280 chip (for details refer to our article called Diamond Stealth S110 Graphics Card Review).
The new Diamond Multimedia had more advanced solutions to offer as well, yet the name of the company didn’t sound as loud on the market as it had used to. Diamond did not offer truly exclusive products. It is only recently that the company caught the spotlight by announcing an update to its Viper series with graphics cards based on ATI Radeon HD 2000 GPUs. The legendary brand returns for real with the announcement of the fastest available version of ATI Radeon HD 2900 XT 1GB that has a graphics processor frequency of 825MHz. Some of these new cards come with the standard GPU and memory frequencies, though. We’ll discuss one such Diamond Viper HD 2900XT 1024MB GDDR4 in this review.
The graphics card is shipped in a standard-sized box. Its black-and-red color scheme is typical of Diamond Multimedia products. The company’s logo is placed on the left of the red band. The box shows a picture of a cyborg, a popular character among graphics card makers. So, although not a masterpiece of design, this box maintains the corporate style of Diamond Multimedia quite well, making the company’s products easily recognizable on shop shelves.
Besides the graphics card proper, the box contains the following accessories:
We’ve got just a minimum of accessories here. This should be enough, though, for the enthusiast who’s planning to build a CrossFire platform out of two Diamond Viper HD 2900XT 1024MB cards. The design of the box and the availability of free games and bonuses do not generally affect the shopping choice of this category of users.
Like all top-performance discrete graphics solutions these days, the product from Diamond is in fact a copy of the reference card and does not differ in anything from any other ATI Radeon HD 2900 XT irrespective of the amount and type of graphics memory. You can see it in the following photograph.
There are no external differences whatsoever. It’s impossible to tell if the given model of ATI Radeon HD 2900 XT comes with 1 gigabyte of graphics memory. You can only learn this from the green sticker on the reverse side of the PCB. Besides serial numbers the sticker reads the card model, which is “ATI RADEON HD 2900 XT 1GB” here. The sticker with the company logo on the cooler is the single indication that we are dealing with a product from Diamond.
The GPU of the Diamond Viper HD 2900XT 1024MB GDDR4 is not overclocked and works at a frequency of 742MHz. It has a standard configuration with 64 superscalar computing units with 5 ALUs in each (for a total of 320 ALUs), 4 texture processors (equivalent to 16 TMUs), and 4 raster processors (equivalent to 16 ROPs). There are no differences from the ATI Radeon HD 2900 XT 512MB GDDR3.
Memory is the only component that sets the two ATI Radeon HD 2900 models apart. The total amount of memory being 1024MB on this card, it carries sixteen 512Mb chips of GDDR4 memory (Samsung K4U52324QE-BC09, 16Mb x 32). The BC09 suffix indicates the slowest model in the series, but it has a rated frequency of 1100 (2200) MHz which is more than enough for the ATI Radeon HD 2900 XT 1GB GDDR4. The Diamond version of the card has a memory frequency of 1000 (2000) MHz, so there’s a small headroom for overclocking left.
The Diamond card has no other difference from the reference ATI card and its design is identical to that of any other Radeon HD 2900 XT. The card is equipped with ATI’s reference cooler whose design was described in our review of ATI’s new graphics architecture called Highly Defined: ATI Radeon HD 2000 Architecture Review. This design with a blower and the exhaust of hot air outside the system case is the most optimal one today in terms of size/performance ratio and is employed by both ATI/AMD and Nvidia.
Using a copper heatsink, the ATI cooler has somewhat worse noise characteristics than the reference cooler of Nvidia’s GeForce 8800 series in 3D applications. It can be easily explained if we recall the fact that the R600 has huge power consumption, over 160 watts in 3D mode. It generates a lot of heat and ATI had to achieve the required cooling efficiency by speeding the fan up since the heatsink could not be enlarged much more. As a result, the Radeon HD 2900 XT has normal dimensions but produces more noise than the GeForce 8800 GTX/GTS. The new card is easy to hear among the noise from other system components in 3D mode.
Like any other ATI Radeon HD 2900 XT, the Diamond card is equipped with two DVI-I ports (with support of audio-over-HDMI), a universal YPbPr/VIVO port, and two CrossFire connectors. Power is supplied to the card via two connectors: a 6-pin and an 8-pin one. The latter connector is loaded the most,a s we have already found out from this article, but you can plug a 6-pin connector into it – this will only deprive you of the opportunity to overclock the card using with the standard options found in the ATI Catalyst driver. All other overclocking tools are going to work normally.
Microsoft has acknowledged that its new and actively promoted operating system Windows Vista does not support multi-GPU technologies inherently. The OS does not redirect the driver’s draw requests to GPUs other than the main one. As a result, only one GPU is used no matter how many GPUs there are in the graphics subsystem, and you get an appropriate resulting performance.
Microsoft released a patch for Windows Vista to address the issue, but notwithstanding Nvidia’s claim that SLI works in the Vista environment, we could not make this technology work with any version of ForceWare available at the moment of our tests, including version 162.22. The appropriate option just did not appear in the ForceWare control panel irrespective of the SLI configuration.
As for the opposing technology, we could easily launch a CrossFire tandem using ATI Catalyst 7.7 and benchmarked its performance in games. So, we guess the Catalyst driver is just better optimized for Windows Vista.
ATI’s technology provided a considerable performance growth in most cases. When the growth was zero or even negative in certain applications, it was due to the specifics of the game engine, not to some incompatibility with Windows Vista. Thus, the situation with multi-GPU support in Windows Vista was like follows at the moment of our writing this review: solutions from the former ATI Technologies were fully operable while Nvidia’s solutions were not. That’s why we did not benchmark GeForce 8800 GTX SLI and GeForce 8800 Ultra SLI configurations for this review.
To test the performance of ATI Radeon HD 2900 XT 1GB CrossFire tandem we assembled the following standard test platform:
Since we believe that the use of texture filtering optimizations is not justified in this case, especially for high-end graphics solutions, the AMD and Nvidia graphics card drivers were set up to provide the highest possible quality of tri-linear and anisotropic texture filtering. We have also enabled transparent texture filtering to achieve best image quality by selecting Transparency antialiasing in multisampling mode for Nvidia GeForce and Adaptive antialiasing for AMD Radeon. As a result, our Nvidia ForceWare and AMD Catalyst settings looked as follows:
We selected the highest possible graphics quality level in each game using standard tools provided by the game itself. The games configuration files weren’t modified in any way. Performance was measured with the games’ own tools or, if not available, manually with Fraps utility version 2.9.1. We also measured the minimum speed of the cards where possible.
Since CrossFire tandem including two Radeon HD 2900 XT 1GB is a high-end solution we performed our tests in 1600x1200, 1920x1200 and 2560x1600 resolutions. The games that didn’t support 16:10 ratio were run in 1920x1440 or 2048x1536 resolutions respectively. We used “eye candy” mode everywhere, where it was possible without disabling the HDR or Shader Model 3.0. Namely, we ran the tests with enabled anisotropic filtering as well as MSAA 4x. We enabled them from the game’s menu. If this was not possible, we forced them using the appropriate ForceWare or Catalyst driver settings.
Besides the Radeon HD 2900 XT 1GB CrossFire tandem we also tested one of these cards in single-card mode. For the sake of more illustrative comparison we also included the following AMD and Nvidia solutions:
For our tests we used the following games and benchmarks:
First-Person 3D Shooters
Third-Person 3D Shooters
Unfortunately, we didn’t have a second Radeon HD 2900 XT 512MB, so we can’t tell you how the alternative to the GeForce 8800 Ultra may perform. On the other hand, you can see that the 1GB version of Radeon HD 2900 XT is hardly any faster than the 512MB version even at a resolution of 2048x1536 pixels. The CrossFire configuration with two new cards is 8-9% ahead of the GeForce 8800 Ultra, and we suppose that two classic Radeon HD 2900 XT cards would be about as fast in CrossFire mode.
So, AMD is victorious save for the fact that two Radeon HD 2900 XT cards are going to consume much more power than a single GeForce 8800 Ultra and also require a high-wattage PSU. But let’s see what we have in other games.
Besides the full version of Call of Juarez we used a DirectX 10 test based on the game.
It’s a victory for AMD once again! Moreover, the Radeon HD 2900 XT 1GB CrossFire is the only solution that is capable of ensuring a really high speed in Call of Juarez. And again, one such card is not much faster than a Radeon HD 2900 XT 512MB. It means that purchasing two rather inexpensive Radeon HD 2900 XT 512MB cards is not only a worthy alternative to the GeForce 8800 Ultra, but also the only means to ensure comfortable gaming conditions at a resolution of 2560x1600 pixels – and for a reasonable price, by the way!
A GeForce 8800 Ultra SLI tandem might have shown even better results but SLI technology is still not supported normally in Windows Vista as yet and it’s uncertain when this problem will be solved.
The image quality in Call of Juarez DirectX 10 Benchmark is considerably higher than in the original game. The more realistic lighting and shadowing model catches the eye in particular. Also notable is the use of complex special effects like parallax occlusion mapping, which make many materials in the game look much better than before.
These beauties are accompanied with a tremendous performance hit, though. The final version of Call of Juarez DirectX 10 may be better in this respect, but so far none of the single graphics cards can ensure an average frame rate of at least 30-35fps in it. The best result is turned in by the GeForce 8800 Ultra, probably due to its 32 texture-mapping units and 24 raster operators.
CrossFire technology doesn’t do any good here. It even provokes a performance hit at a resolution of 1280x1024. This problem will probably be solved in the final version of the game. Display resolutions higher than 1920x1200 should also be supported, although they don’t make much sense considering the low performance of today’s DirectX 10 compatible solutions.
Oddly enough, the pair of Radeon HD 2900 XT 1GB cards refused to work in CrossFire mode when we enabled 4x FSAA: the results would be always lower than those of the single card.
It’s different when we enabled HDR without FSAA: CrossFire technology works correctly and the Radeon HD 2900 XT tandem is in the lead. It enjoys the biggest lead over the GeForce 8800 Ultra in 1600x1200 and 1920x1200 whereas in 2560x1600 Nvidia’s card almost overtakes the ATI/AMD platform. The frame rate is high enough for normal play everywhere, which is natural considering the age of the game.
The new generation of CrossFire systems doesn’t look brilliant here. The pair of Radeon HD 2900 XT 1GB cards (and of ordinary Radeon HD 2900 XT as well) is competitive against the GeForce 8800 Ultra in the resolutions of 16:10 format, but the minimum speed provided by such a pair is not high enough for comfortable play. Moreover, the CrossFire tandem acts up in 1600x1200, suffering a performance hit for some reason.
Using the deferred rendering technique, this game is incompatible with full-screen antialiasing. That’s why there are only anisotropic filtering results here.
Ghost Recon Advanced Warfighter proves to be fully compatible with the multi-GPU technology from AMD, and the new-generation CrossFire systems show their best here: the Radeon HD 2900 XT 1GB tandem surpasses the GeForce 8800 Ultra at every display resolution in terms of both average and minimum speed. And like in the previous tests, the same is going to be true for a pair of Radeon HD 2900 XT cards because the single Radeon HD 2900 cards deliver almost the same performance even at a resolution of 2560x1600 pixels. The game seems to have enough of graphics memory as well as of memory bandwidth – the increased clock rate of GDDR4 memory installed on the Radeon HD 2900 XT 1GB is just not called for.
The Radeon HD 2900 XT 1GB has no advantage over the model with 512 megabytes of GDDR3 memory, so we can suppose that the results of the CrossFire platform are going to be the same for the other possible CrossFire configuration. And these results are impressive in comparison with any of the single cards, including the GeForce 8800 Ultra. The average speed is over 150fps even at 2560x1600 with enabled 4x FSAA. The Radeon HD 2900 XT CrossFire even seems to hit the ceiling imposed by the CPU performance in the lower resolutions.
CrossFire technology works normally in the OpenGL environment, providing a 70% performance gain for the Radeon HD 2900 XT 1GB pair in comparison with the single card at 1920x1200 resolution. The single such card is only 1% ahead of the Radeon HD 2900 XT 512MB.
The game doesn’t support FSAA when you enable the dynamic lighting model, but loses much of its visual appeal with the static model. This is the reason why we benchmarked the cards in S.T.A.L.K.E.R. using anisotropic filtering only.
The problem with the performance of the Radeon HD 2900 series in S.T.A.L.K.E.R. we noticed before still persists. Although the use of CrossFire mode brings about a considerable performance gain, the minimum of speed remains very low. The average frame rate is far from ideal, either, being higher than 40fps in 1600x1200 only.
This is one of the few cases when investing into two Radeon HD 2900 XT is not as rewarding as purchasing a single Nvidia GeForce 8800 Ultra.
Like in the other cases, there is little to no difference in performance between the two versions of Radeon HD 2900 XT with the same core frequency. The Radeon HD 2900 XT CrossFire is competitive against the GeForce 8800 Ultra in terms of average frame rate but has a lower minimum of speed. Anyway, the CrossFire system allows playing normally in resolutions up to 2560x1600 inclusive with enabled FSAA.
This is one of the few games the multi-GPU technology from ATI fails to work correctly in. That’s why the Radeon HD 2900 XT CrossFire proves to be even slower than the single card irrespective of the amount and frequency of graphics memory. Note, however, that enabling the CrossFire mode leads to a considerable growth in the minimum speed at 2560x1600, which means that the second GPU’s resources are utilized, at least partially. The malfunctioning of CrossFire technology in this test must be due to some special features of the game engine.
We try to get the highest possible image quality from each game, but Splinter Cell: Double Agent cannot use FSAA and FP HDR simultaneously. That’s why the results refer to the HDR + 16x AF mode only.
Turning CrossFire technology on leads to a performance hit, but the single Radeon HD 2900 XT is fast in both versions (with 512MB of GDDR3 and with 1024MB of GDDR4), being just 11% slower than the expensive and rare GeForce 8800 Ultra. So, this game shouldn’t be a problem for those people who are about to build a graphics subsystem with two Radeon HD 2900 cards.
The current version of the game doesn’t support FSAA, so we performed the test with anisotropic filtering only.
This game is not compatible with CrossFire, either: the min speed of the CrossFire system is lower than that of the single Radeon HD 2900 XT. As opposed to Splinter Cell, the game obviously prefers Nvidia’s GPUs, and products developed at ATI Technologies don’t provide an acceptable speed in high resolutions.
The current version of the game still doesn’t support HDR normally, so we perform the test in the eye candy mode with 4x FSAA.
The Radeon HD 2900 XT 1GB CrossFire behaves oddly here. Its performance is roughly equal to the GeForce 8800 GTS in resolutions up to 1920x1200, but then it seems to get a second wind in the most resource-consuming 2560x1600 resolution, outperforms the GeForce 8800 Ultra, and ensures a playable frame rate. We can’t yet explain this phenomenon.
The game loses much of its visual appeal without HDR. Although some gamers argue that point, we think TES IV looks best with enabled FP HDR and test it in this mode.
The two Radeon HD 2900 XT cards working in CrossFire mode show their best at 2560x1600 resolution where none of the single graphics cards can match their performance. At the lower resolutions this system is about as fast as the single GeForce 8800 Ultra. As usual, there is no difference in speed between the two versions of Radeon HD 2900 XT.
It’s somewhat different in the open scenes of the game. The CrossFire system steps up to the level of the GeForce 8800 GTX at a resolution of 1920x1200 only and becomes a true leader in 2560x1600. Of course, it delivers high performance for you to play the game normally. The single Radeon HD 2900 XT cards behave like in the other tests because the memory bandwidth is not a bottleneck for these solutions with their 512-bit memory bus.
CrossFire is only effective from the 1920x1200 resolution in which the pair of ATI Radeon HD 2900 XT is about as fast as the GeForce 8800 Ultra in terms of average frame rate but somewhat slower than the Nvidia solution in terms of minimum speed. The CrossFire system is behind the GeForce 8800 Ultra at 2560x1600 resolution, yet its speed is still high enough for maximum playing comfort.
This game having a frame rate limiter, you should compare the minimum frame rates in the first place because it is the minimum speed that determines your playing comfort in Command &Conquer 3.
Today’s top-end graphics solutions can’t be compared in this test at resolutions below 2560x1600 because they all reach the frame rate limiter and have a solid reserve of speed. At 2560x1600 CrossFire technology helps ATI’s solutions reach the level of the GeForce 8800 GTX/Ultra: the single Radeon HD 2900 XT can’t do that in either of its versions despite its high-performance memory subsystem.
The use of two Radeon HD 2900 XT 1GB cards in CrossFire mode leads to a performance growth, but this configuration is comparable only to the GeForce 8800 GTS and does not allow to play normally at 2560x1600 resolution with enabled antialiasing. Perhaps things will improve for the better with newer versions of Catalyst, but the GeForce 8800 Ultra is so far the best choice for playing Supreme Commander.
We don’t use the eye candy mode in this game due to its having problems with FSAA. We test it with anisotropic filtering only. The version 1.70 patch adds DirectX 10 support, so we ran the game in two modes, DirectX 9 and DirectX 10.
The CrossFire platform is victorious once again. Like in the previous test, this is true for both versions of Radeon HD 2900 XT in the tandem. It’s only in 2560x1600 that the single Radeon HD 2900 XT with the faster GDDR4 memory is about 5% ahead of the junior model. This is one of the most successful tests (another one is the 2048x1536 resolution in Battlefield 2142) for the new graphics card. Note that the Radeon HD 2900 XT 1GB CrossFire platform and the GeForce 8800 Ultra offer a comparable reserve of speed at a resolution of 2560x1600 pixels.
We can’t say DirectX 10 makes the game much more attractive. Company of Heroes was originally developed within the DirectX 9 framework after all. However, the lighting of the scene looks better in this mode. Shadows are softer and more realistic, and smaller details look better due to the new special effects. The shader-based grass, which is missing in the DirectX 9 mode, looks particularly good. The physical model is improved in the DirectX 10 mode, too.
The tradeoff for this is a terrible performance hit in the DirectX 10 mode: the Radeon HD 2900 XT 1GB CrossFire tandem can hardly yield 27fps with slowdowns to 12fps in 1600x1200! The GeForce 8800 Ultra isn’t any better: only 30fps with slowdowns to 10fps. The less advanced DirectX 10-compatible solutions look even more depressing. Of course, there’s no talking about normal play in the DirectX 10 mode: the improvements in the image quality area are not so deep as to justify the terrible loss of speed.
The overall 3DMark05 scores show the lack of any advantage of the newer, 1GB, version of Radeon HD 2900 XT over the older one, which is equipped with 512 megabytes of graphics memory. The difference of 129 points is likely to be a measurement error.
The results of the CrossFire platform are indicative of the possibility for the user to build a graphics subsystem with a higher overall performance than that provided by a single GeForce 8800 Ultra and for a comparable sum of money because you don’t have to buy two Radeon HD 2900 XT 1GB cards. It’s quite enough to have two ordinary models with 512 megabytes of memory on board. This is confirmed by the results we’ve got in a number of games. But before we make up our final opinion, we want to examine the results of individual tests we got in high display resolutions with enabled 4x FSAA.
As was to be expected, the CrossFire platform is faster than the GeForce 8800 Ultra in each test, except for the first one, which demands a high fill rate from the graphics card. The results agree with the overall scores although the latter were obtained at a display resolution of 1024x768 without FSAA.
The CrossFire tandem enjoys a big lead over the other test participants, scoring over 13.000 points. The best result among Nvidia’s single-card solutions is 11,462 points. Since both models of ATI Radeon HD 2900 XT have the same result, a CrossFire tandem made out of two cards with 512MB of graphics memory will be just as effective in outperforming the GeForce 8800 Ultra.
As we had anticipated, the pair of Diamond Viper graphics cards comes out the winner in both categories of tests, but it enjoys a bigger lead over the GeForce 8800 Ultra in the SM3.0/HDR tests. The total of 32 TMUs and 32 raster processors prove to be enough to get rid of the R600’s bottleneck whereas the combined power of 640 shader processors leaves no chance to the opponents where sheer computing is necessary.
The results of individual tests launched at high resolutions with enabled full-screen antialiasing produce a somewhat different picture. The CrossFire tandem doesn’t take first place in the first test although looks competitive against the GeForce 8800 GTX/Ultra. As for the single performance of the ATI Radeon HD 2900 XT cards, they are inferior even to the GeForce 8800 GTS, and the 1GB model is considerably faster than the model with 512 megabytes of GDDR3 memory. The computing capabilities of ATI’s architecture are not called for here.
The SM3.0/HDR tests are quite a different story. Here, the two Diamond Viper HD 2900XT 1024MB GDDR4 cards working in CrossFire mode deliver almost two times the performance of the GeForce 8800 Ultra in both first and second tests. Moreover, both versions of ATI Radeon HD 2900 XT are very close to the GeForce 8800 Ultra in single-card mode in the first test where they are limited by the number of texture and raster processors and outperform the Nvidia card significantly in the second test, which is not so sensitive to the texture-mapping speed.
All in all, the 3DMark06 results confirm the fact that the ATI Radeon HD 2000 architecture is better suited for modern gaming conditions that require a high computing capacity from the GPU. On the other hand, the fact that the R600 has got one bottleneck – a too small number of texture and raster subunits – is confirmed as well. The answer to the main question of this review is clear, too. The ATI Radeon HD 2900 XT CrossFire configuration is quite a worthy alternative to the Nvidia GeForce 8800 Ultra.
Notwithstanding the unofficial arrival of the new graphics card, we can regard it as an established fact that the Radeon HD series has acquired a new model that pretends to be its flagship product. As was to be expected, the Radeon HD 2900 XT 1GB, at least in its version with the standard graphics core frequency, does not deliver anything exceptional in terms of gaming performance. On the other hand, the ATI Radeon HD 2900 XT 1GB in Diamond Multimedia’s implementation is a well-made and appealing product with its specific features and, unfortunately, drawbacks.
It is clear that modern games do not need more than 512 megabytes of graphics memory even for extremely high display resolutions with enabled full-screen antialiasing. The increase of the memory frequency from 1650 to 2000MHz cannot be very profitable for a 512-bit memory bus, especially as the memory subsystem is not the main bottleneck in the R600 architecture. As a result, the ATI Radeon HD 2900 XT 1GB is only 4-5% ahead of its 512MB predecessor at best. More often, the two cards deliver similar performance.
So, there is no wonder AMD decided not to announce the Radeon HD 2900 XT 1GB officially. Delivering almost the same performance as the Radeon HD 2900 XT 512MB but coming at a higher price, this card wouldn’t make a valuable addition into the official ATI Radeon product range. This card is obviously targeted at enthusiasts who are into overclocking. Pre-overclocked versions of Radeon HD 2900 XT 1GB are offered for this category of users as well. Practice suggests that, joined into a CrossFire tandem, such graphics cards can become the means to set new records in 3DMark.
A CrossFire tandem made out of two ATI Radeon HD 2900 XT cards is quite a different thing. Costing about $800-1000, which is comparable to the price of a GeForce 8800 Ultra, this configuration outperforms the Nvidia solution across a number of applications. Our testing has shown that ATI CrossFire technology enjoys a solid support in Windows Vista, obviously due to the high-quality Catalyst driver for the new OS.
It’s only in four out of 23 cases that ATI/AMD’s multi-GPU technology failed to provide a performance growth in comparison with the single card. In the other games from our list the technology worked smoothly, increasing the speed up to 80-90%. We want to specifically note that the AMD CrossFire platform proved to be the only solution to ensure an acceptable speed at 2560x1600 resolution in Call of Juarez and Neverwinter Nights 2. Thus, if not the best solution in the $800 category, the ATI Radeon HD 2900 XT CrossFire is a worthy rival to the Nvidia GeForce 8800 Ultra. Its main drawback is the indecently high level of power consumption, about 320 watts in 3D mode, and it is very noisy, too. These two factors call for a roomy and well-ventilated system case and a high-wattage, expensive PSU.
As for Nvidia’s multi-GPU solutions, the support of SLI technology in Windows Vista is deficient so far despite the release of an appropriate patch by Microsoft. We installed that patch but could not enable SLI mode on our test computer. Anyway, as soon as this problem is corrected, the appeal of the ATI CrossFire platform may lessen somewhat in the eyes of PC enthusiasts.