ATI Radeon HD5970 dual GPU graphics card

THIS YEAR is the first one in quite a while to see ATI, now a proud part of AMD, trounce Nvidia on the top-end 3D graphics turf. A combination of earlier 40nm process adoption, smaller GPU dies and a modular approach helped ATI get its latest generation parts out pretty much on time. We already saw the HD5870 performing in both single and Crossfire dual GPU versions. Now, here's the widely expected - and still in very short supply - ATI HD5970 dual GPU card in a single slot.

Just a bit bigger and longer than its already large single GPU cousin, the HD5970 abandons ATI's old 'X2' moniker for the dual GPU cards, going for a distinct base product number instead, a whole 100 points more. How does it compare with the two HD5870's in Crossfire? Well, before we go to the benchmarks, a couple of pointers.

Unlike the old HD4870X2, which had the same GPU and memory speed as the HD4870, the HD5970 GPUs and memory clock speeds are somewhat slower, in fact up to 20 per cent slower by default, versus the HD5870. Core GPU speeds dropped from 850MHz - often pushed to 900MHz and more on most 5870 cards - to 725 MHz, and memory speed fell from GDDR5-4800 to GDDR5-4000. Handling the excess heat from two GPUs and the associated PCIe bridge, as well as the power feed limitations, may have enforced these clock speeds down. On the other hand, if better cooling is used, and the space provided for dual 8-pin power connectors goes with the additional pins, there's no reason why we couldn't go for, say, a dual 900 MHz GPU setting. The problem is that the existing cooling is actually a pretty nice piece of work already - dual vapor chambers with heat pipes and such - so I wonder if some kind of chilled liquid cooling system will be needed instead to get even more speed out of these cards. Liquid cooling blocks can also bring the much valued single-slot thickness to allow two-card CrossFire setups without sacrificing too many other slots, albeit with the usual liquid cooling leak risks.

The display output options aren't the same as on the well port-endowed HD5870, as the extra fan outflow space allows for only two DVI and one DisplayPort connector here. Talking about multi-display work, I'd really like a 2 x 2GB memory version in order to have more RAM space to support the chains of high-resolution screens that are possible now with ATI's EyeFinity feature.

The card is far hotter running than the HD5870, despite having fan out openings at the card top as well. In fact in the - failed, by the way - CrossFire attempt with one HD5970 and one HD5870 running side by side, the heat felt from the two cards was many degrees apart. The HD5970 became too hot to touch within a few minutes, while the HD5870 stayed reasonably cool all the way, the same as it was when ran on its own prior to the HD5970 arrival. It's obvious why ATI had to reduce the clock speeds on the dualie.

We ran the HD5970 on the same test setup as the two HD5870 cards last week. Same drivers and benchmarks were used, too, until we discovered that the Catalyst 9.11 driver couldn't be used, but instead we had to use a specific beta driver from the AMD site. Here they are, in the default mode without any overclocking, followed by the dual HD5870 results.

Hmm, compare the results - it looks like the difference matches the clock speed drop from 850MHz to 725MHz on the GPU, nicely. Since the card price is, on average around $600, also a bit less than what you'd shell out for a pair of HD5870 units, the positioning makes sense.

Our next HD5970 benchmark run will also cover GPU computing, which is becoming increasingly important, and this card provides 4.5 TFLOPS of theoretical single-precision floating-point throughput, plus nearly 1 TFLOPs of double-precision floating-point performance, seven times as much as a high-end Dual Xeon workstation. Of course, those Xeon GFLOPS are usable by almost any software, while the GPU GFLOPS need recompilation, tuning and tweaking, and quite bit of it.

In summary, the world's fastest 3D graphics card shows leading test results, but it could have been even faster if not for its cooling and power limitations. I hope to see a faster clocked 2 x 2GB RAM version with better cooling as well as 2 x 8-pin power to feed all that. However, even without that, ATI still firmly holds the performance lead in graphics for now. If only its AMD CPU counterparts could pull off such a coup versus Intel, eh? µ

Good
Top performance for a decent price.

Bad
More Crossfire optimised game titles are still needed.

Ugly
Fails to reach its full potential due to power and cooling constraints.

Beers
8/10