Labs

The Radeon HD 3870 sits at the top end of ATi's mid-range offerings and it's proved hugely popular since its launch. Like the HD 3850, it's a 55nm part with 666 million transistors and 320 stream processors. It supports DirectX 10.1, Shader Model 4.1 and the PCI Express 2.0 interface, and is CrossFire-compatible.

It's worth noting that the HD 3870 X2 is essentially two of these GPUs crammed onto a single, very large, board, which has now fallen in price to more sensibly reflect the cost of two individual HD 3870s.

The HD 3870 improves over theHD 3850 with a core clock of 775MHz- compared with 670MHz - and 512MB of cutting-edge GDDR4 memory, running at an effective 2.25GHz

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compared with 1.66GHz GDDR3. Other than that, they're the same card, with a 256-bit memory bus and similar dimensions. Both require a power supply with plenty of grunt: 450W is recommended, or 550W to run two of them together.

The good news is that this card is only about £20 dearer than the 512MB HD 3850, but offers a significant step up in performance. In Crysis, it was faster at 1,280 x 1,024 and Medium settings by 14%, and the gap increased to 26% when we upped the resolutionto 1,600 x 1,200 and High settings. It topped its lesser sibling by similar margins in Call of Duty 4, too: 41fps, compared with 34fps, in our High settings test.

But its closest rival is really Nvidia's 9600 GT. That card was close behind in our Crysis Medium test, with 50fps, also managing an impressive 21fps in our High test, and moving in front with faster results in all of our Call of Duty 4 tests. The 9600 GT will cost you a few pounds less than the HD 3870, at least until ATi fights back with the inevitable price cuts, but both are attractive for the more cost-conscious gamer.

If you can't afford another £50 for the 8800 GTS 512MB, your choice is between this and the 9600 GT. Given its slightly lower price, we'd just about lean towards the GT.