ATI Radeon HD 5970 is top model, and as such, it is intended for users that want, or need, top performance levels without any compromises and questions asked. Radeon HD 5970 has two RV870 GPUs and as such, it presents ATIs pinnacle when it comes to multiGPU graphics cards. This GPU is DirectX 11 compatible with support for Shader Model 5.0. Since HD 5970 has two GPUs on one PCB, it is recognized as one graphics card. Two GPUs communicate thanks to second-generation PLX chip that acts as bridge between two GPUs. Memory bus is declared as double 256bit, because memory chips found on these cards are GDDR5. When it comes to sheer numbers, HD 5970 should be twice faster than its single GPU cousin HD 5870. When it comes to Eyefinity, in case of HD 5970 it supports CrossFire, which is nice improvement compared to HD 5870 model.

Since we got sample model directly from ATI we don’t have to waste your time on descriptions of packaging and additional accessories because there are none. Graphics card is huge, but to be honest not that much bigger than Radeon HD 5870.

Of course, main difference is easily noticeable when both card are turned on their backs. However, these are just visual differences.

Real differences are under the bonnet. Two molex connectors (6-pin and 8-pin) combined with PCI-Express 2.0 slot can provide maximum of 375W or power. Besides this combination, on PCB is also left possibility of mounting two 8-pin molex power connectors, in which case this card could use maximum of 450W. This combination is probably reserved for overclocked models that manufactures will offer as soon as possible.

Cooling solution looks the same as on HD 5870 model, but it isn’t the same. Aluminum profile under the black plastic cover is larger and heavier which can be also sad for two copper bases. This cooler should be enough for 400W thermal dissipation. Obviously there is “breading space” of 100W left for overclocking models which is nice. ATI marketing department realized potentials of overclocking and started promoting this card as perfect overclocking material, but the fact remains that ATI lowered frequencies for HD 5970 compared to HD 5870 model. If this was NVIDIA graphics card, this wouldn’t be surprise. In case of ATI HD 3870X2 and HD 4870X2 models, frequencies were identical to HD 3870 and HD 4870 models, respectively. In case of HD 5970 and HD 5870 it is not the case. Therefore, this “huge” overclock margin isn’t that huge as the matter of fact. When you reach default HD 5870 clocks on HD 5970 you have already raised GPU clock for hefty 125MHz and 200MHz for memory. Of course, HD 5970 does not stop at those values. Because of lowered frequencies HD 5970 at default frequencies consumes “only” 297W, but we were actually surprised with power consumption in IDLE of only 47W. This low power consumption is achieved by “shutting down” or “putting asleep” one core.

When it comes to overclock margins this card definitely didn’t disappoint. Since it has 0.8ns memory chips on PCB, which could operate at 1250MHz, it is obvious that additional 250MHz can be reached without too much trouble. Despite our determination and optimism, we hit the wall at very respectable 1300MHz for memory. Detail that makes HD 5970 model such interesting model for enthusiasts, is presence of Volterra voltage regulators on PCB. This means that voltages on this card can be controlled by software, which is great news. At default voltages, GPU cannot reach more than 790MHz, which is good, but not great result. Great results can be achieved by using software that is provided by ATI itself, and that allows you to raise voltages for GPU. Thanks to this feature even 1GHz is not that hard to reach, which is great result for an GPU of this complexity. In addition, by using software voltage regulation, possibilities of making fatal damage to your graphics card are minimal, but not eliminated.