14 DAY TRIAL // Advanced Micro Devices decided it was high time to give us a glimpse at its upcoming ATI Radeon HD 4870 X2, due to an official launch in approximately a month. What we see when looking at R700 is basically a board made of maximum two RV770s connected through a PCI Express switch. The card features the same core speeds as Radeon HD 4870, and with 512MB of memory size per graphics processor.
Basically, we would expect to see a board performing the same manner as a pair of 4870 cards connected via CrossFire. Yet, AMD announced that it is undergoing intensive work on a new technology based on the GPU to GPU communication, something CrossFire did not do at all, so we're looking at something different from the beginning. While in CrossFire, the two GPUs worked independently, each responsible for some part of the screen, with results mixed by a combiner, R700 changed that by allowing the GPUs effectively communicate.
No specific information on how deep the communication will go, what info will be shared or on how much are the bandwidth requirement increased have been revealed until now. The main idea behind the single-card multi-GPU might be, after all, the shared framebuffer. Still, it seems that R700 does not do the things right at the moment, as each GPU needs a copy of all textures, geometry, and so on, all ending in resources waste and performance limitations. Though having 1GB of memory, each processor uses only half, so the card goes down to the performance of a 512 card.
We would have some specific expectations from the multi-GPU technology, and no doubt that they may differ from the course the actual technology will have, but AMD's pursue needs to be appreciated. This peek inside its kitchen is also a good thing for the company. On the other hand, AMD should really consider that users need compatibility, reliability, and consistent performance in any new card to put it on the podium.
The card itself is a rather large one, but still compact considering the two GPUs and 1GB of GDDR5 memory it packs inside. The RAM goes on the back of the card, along with a plate, as on the 3870 X2 (the 4870 has all it's RAM featured up front).
R700 outperforms RV770 in all tests
AMD allowed reviewers to do some testing on the card, but also had some demands for the process. As the card offered at this moment is not the final product, no detailed information on the architecture is to be revealed yet. Also, testing has been limited to only four games or artificial benchmarkings per review, while Power tests were denied, due to PowerPlay not being enabled in the BIOS. The final card that will be released on the market is said to have all the features enabled and to be fully functional.
The guys from anandtech tested the card using Age of Conan, Crysis, The Elder Scrolls IV: Oblivion and Race Driver GRID, and compared the results to those obtained when testing 4870 in CrossFire, since the R700 nears that performance. The results for other tested cards have been included in the comparison chart as well.
The results placed 4870 X2 on top of the performance list when playing Age of Conan and Race Driver GRID, outperforming all other cards by far from the last game. It seems that R700 scaled nicely at 2560x1600, while other cards, including those in CrossFire, barely went through the menus and entered the game. Although this test does not say it all, the improvements AMD has brought with the new technology are tangible.
Crysis placed the card somewhere near the middle of the list, but still in the upper half. The performance results are close to those revealed by CrossFire. Yet, it is worth mentioning that SLI scales better than CrossFire when it comes to Crysis. Finally, Oblivion placed the card second on the list, again after Nvidia's SLI, but in front of CrossFire. R700 placed in front of the multi-card technology from AMD at all tests, it should be mentioned.
Since the game tests show improvements, a fast look at the power consumption and generated heat and noise come next. 406W under heavy load marked R700, still lower than 4870 in CrossFire. The heat level is lower than on a single 4870 as well, perhaps due to the heavier HSF. The noise level remains lower than that of a GTX 280 even at max fan speed. The final product should allow more testing and, perhaps, even better results.
In the end, HD 4870 X2 outperformed the single GPU RV770 in all tests, even in the CrossFire part. This high-end card aims at revolutionizing the industry for sure, but AMD should consider making CrossFire high scalable on all the games, too. Since the drivers proved to be somehow faulty on the compatibility part, the main focus should be on their quality, since the hardware part works good enough. Game developers will also have a word in this, as their programming techniques influence the results as well.
AMD may be on its way to get big scores with its high-end 4870 X2 graphics card after all. Also, the card is expected to reach the market at a price tag set over $500.
