ATI Radeon HD 5970

ATI’s latest graphics card breaks from convention in more ways than one. Its name, for instance, doesn’t follow the precedent set by the dual-GPU Radeon HD 3870 X2 and HD 4870 X2 cards, and it’s also the largest graphics card we've ever seen, dwarfing our test motherboard at 32cm in length and weighing a socket-endangering 1.2kg.

The card’s specification continues to raise eyebrows. Two GPUs, based on the impressive Radeon HD 5870, boast a combined 3,200 stream processors and 4.3 billion transistors, and the 725MHz core clock generates a massive 4.65TFLOPS of computing power – far more than the 1.78TFLOPs of Nvidia’s most powerful chip, the GeForce GTX 295, or the 2.72TFLOPs provided by the HD 5870.

Elsewhere, the new 40nm cores are partnered with 2GB of 1,000MHz GDDR5 memory, while the RAM’s 256GB/sec of bandwidth is the highest we’ve ever encountered on a graphics card.

This mouth-watering list of specifications delivered, as expected, the best benchmark results ever. When placed in our test rig, which consists of an Intel Core i7-920 processor, MSI X58 Platinum motherboard and 2GB of DDR3 RAM, the HD 5970 blew away our three standard Crysis benchmarks, delivering a result of 62fps in our high-quality 1,600 x 1,200 test.

It wasn't troubled by more demanding quality levels and resolutions, either: the HD 5970 ran through our 1,920 x 1,200 very high quality test at 48fps, with this figure dropping to a still-playable 31fps when we upped the resolution to 2,560 x 1,600.

The HD 5970’s world-beating performance, though, comes with several major caveats. The first is the card's size, which will be too much for many PCs. We also found the HD 5970 both hot and loud. Even with such a large housing the two GPUs ran at 90 degrees after mere minutes of running our benchmarks, and the fan – which ran at around 25% of its 4,000rpm maximum speed – proved distracting even against a background noise of office air conditioning. We wouldn’t fancy being accompanied by its constant whine in a quiet living room or study.

And, while ATI is keen to boast about the HD 5970’s green credentials at idle it's still pretty hungry when pushed. Our rig idled at 143W, which isn't bad for a card this powerful, but those power demands shot up to 322W at peak performance – 70W more than the ATI HD 5870.

But perhaps the main problem - if you can find one at all with retail stocks not exactly overflowing - is the price. At around £451 exc VAT it’s nearly double the cost of an HD 5870, our current A List champion, and it’s hard to justify such an outlay when ATI's latest single-GPU card will cope effortlessly with any game you care to throw at it.

Price when reviewed: £452 (£520 inc VAT)