@ Tech Report
Although the Hynix chips on our engineering sample are rated for up to 4Gbps operation, on this board, they run at the same 900MHz base clock and 3600MT/s data rate as on the Radeon HD 4870. That ain't exactly shabby, though. All told, the R700 has an aggregate 512-bit path to memory that theoretically peaks at 230GB/s. To put that into perspective, its likely closest competitor, the GeForce GTX 280, has "only" 142GB/s of peak memory bandwidth. With that in mind, the big question about the 4870 X2 is: How does it perform? If you've answered "About like two Radeon HD 4870s in a CrossFire setup," you're on the right track. Compared to a dual-card config, this puppy has the potential benefit of a faster CrossFire interconnect between the GPUs and twice the effective memory size (single 4870s currently have 512MB), but it has the possible disadvantage of those GPUs having to share PCI Express bandwidth to the rest of the system via that PLX switch. Which, of course, is why we test these things....
The "Scalable design" block we already know about, that's RV770 - we reviewed it last month. The 150W TDP $300 part is the Radeon HD 4870, and the 110W $200 part is the Radeon HD 4850, the two cards that have caused NVIDIA quite a bit of pain already. The smaller $100 part has a name, and a release date, neither of which we can talk about at this point, but it's coming. Today however, is about the 250W, $500 multi-GPU solution - internally known as R700. Hot on the heels of the Radeon HD 4800 series launch, AMD shipped out ten R700 cards worldwide, attempting to capitalize on the success of the 4800 and showcase the strength of AMD's small-GPU strategy. We're assuming that AMD will call the R700 based cards the Radeon HD 4870 X2, and based on the chart above we're expecting them to retail above $500 (possibly $549?). Today's article is merely a preview as R700s won't be officially launched for at least another month, but AMD wanted to unveil a bit of what it's cooking.
There is nothing intrinsically clever about what ATI is doing here. Much in the vein of the also-twin-GPU Radeon HD 3870 X2, the new card positions two of its fastest-clocked single-GPUs - HD 4870s - on to one card. The difference here is that the HD 4870 X2's frequencies are exactly the same speed as the regular cards', running at 750MHz core and shaders and 3,600MHz for the smokin' GDDR5 memory. Each of the card's twin GPUs has access to its own 512MiB frame-buffer, of course, and both are connected via a PCIe 2.0 conduit that's mounted on to the PCB. The card-based numbers are extraordinary; 2.4TFLOPS of math calculation; 60Gtexels/s of bilinear filtering; and 230GiB/s of combined memory bandwidth - comfortably higher than any card that's come before. It would not be unreasonable to assume that performance will be very much akin to two discrete Radeon HD 4870 boards placed in two-way CrossFire.
@ PC Perspective
Not too long ago the idea of a multi-GPU graphics card seemed taboo and brought about a lot of negative connotations with it. The GeForce 7950 GX2 was the first in the modern NVIDIA/ATI era and some board partners went in other multi-GPU directions until the Radeon HD 3870 X2 was released. We took the 3870 X2 as an answer to NVIDIA's high end cards because the company didn't have a single GPU that could compete with the competitions parts on its own; something of "we need answer" product. Today's preview of the HD 4870 X2 card from AMD proves that this time AMD was planning ahead. Our review of the RV770-based Radeon HD 4850 and HD 4870 cards showed the new GPU architecture to be very potent indeed and NVIDIA is very scared of what the dual-GPU version, known as R700 previously, would do to its line of cards. Today we were allowed to post a short "preview" of the card's performance and I have to say you will likely be impressed. The Radeon HD 4870 X2 card is AMD's answer to NVIDIA's flagship GTX 280 card in terms of pricing and placement. Even though NVIDIA recently dropped a bomb and lowered the price of the GTX 280 from $649 to $499, the estimated pricing we have seen for AMD's card is in the ">$500" range and will likely fall on the lower end of that open-ended range now. Isn't competition a wonderful thing?
@ Legit Reviews
Only four short months ago AMD launched the Radeon HD 3870 X2 graphics card and it was the flagship ATI Radeon product. ATI took two RV670 cores (Radeon HD 3870) and put them on the same PCB with the same amount of memory with the bridge chip already on the video card that enabled CrossFire automatically. The result was a graphics card that has two RV670 cores with 1GB of GDDR3 memory at a price point of $449. A Radeon HD 3870 X2 can now be found for just $289 and still packs some serious performance in a single graphics card. Now, the successor to the ATI Radeon HD 3870 X2, the ATI Radeon HD 4870 X2 is here with twice the gaming performance of the last generation. AMD has once again taken two of the latest cores (RV770) and placed them on a single PCB. AMD kept the clock frequencies the same as the Radeon HD 4870 graphics card, so basically you have the power of a pair of those running CrossFire on a single PCB! Our review of the HIS Radeon HD 4870 showed it to be a performance winner at a very nice price point. AMD has once again created a price versus performance winner and they have produced a product that has NVIDIA worried as they don't have a card that competes at the same price point. The GeForce GTX 280 is the only card that stands a chance to the Radeon HD 4870 X2!
So what is the Radeon HD 4870 X2, or better known internally as R700? The Radeon HD 4870 X2 is AMD’s single video card solution for the high-end gaming enthusiast crowd. The Radeon HD 4870 X2 is poised to compete directly with NVIDIA’s GeForce GTX 280 at a competitive price. Final pricing and specifications will be finalized at launch later this summer. The Radeon HD 4870 X2 is simply a video card with two Radeon HD 4870 GPUs on a single board. Therefore each GPU is operating in a “CrossFire” type of configuration, but hard wired on the board itself with a bridge chip. The new Radeon HD 4870 X2 uses a newer bridge chip that supports PCIe 2.0 and AMD has also improved the bandwidth between the GPUs. The bandwidth between both GPUs has been bumped from 6GB/sec, as found on the Radeon HD 3870 X2, to 20GB/sec on the Radeon HD 4870 X2. AMD has also beefed up the RAM on the Radeon HD 4870 X2; our samples have 1GB of GDDR5 accessible to each GPU (so 2GB total on the board.) Now, this memory is still not completely shared, the framebuffer is still duplicated and the memory is not combined. However, due to some inherent evolutionary upgrades present in GDDR5 memory modules there is actually a method in place to share some data between modules using that 20GB/sec bus. All of these improvements are evolutionary, through the memory, and the bridge chip, and should help improve performance and consistency with the Radeon HD 4870 X2 since it is a dual-GPU solution.