ATi Radeon HD 3870 X2

The Radeon brand has a long and proud history, but for the past year ATi - the graphical wing of AMD - has been playing catch-up, while rival Nvidia has set the pace, consistently bringing more powerful hardware more quickly to market.

But AMD isn't quitting yet. Rather than be left behind, the company has boldly retired its entire range of DirectX 10 graphics cards just nine months after launch, replacing it with the updated HD 3000 series.

The new cards use a 55nm fabrication process, promising lower costs and power consumption than the 65nm and 90nm wafers AMD used before (and which Nvidia still uses).

The new cards also support DirectX 10.1, which permits more powerful lighting techniques than the original release of DirectX 10, although it remains to be seen whether developers will target the new routines that aren't currently supported by Nvidia.

We weren't blown away by the first two cards in the new range (the HD 3850 and HD 3870). They're affordable enough, but in our tests they seemed a little underpowered for modern games. AMD's new card, however, has the potential to really shake things up.

As the name implies, the HD 3870 X2 is built around two HD 3870 ASICs mounted on a single card. This isn't a huge technological breakthrough - it's fundamentally the same as running two 3870s in a CrossFire configuration.

So although Windows sees it as one card, as far as CrossFire is concerned it's still a two-device setup and that means the four "card" limit still applies. We're sorry to have to report that you can only run two X2s simultaneously, not four.

Not surprisingly, the X2 thus offers the same feature set as the 3870, including hardware HD video decoding and software power management. Software overclocking should also be possible once driver support is added.

The cramming of two GPUs into one card results in a bulky physical design, and a board that's so long you might need to shift some drives around to accommodate it. It demands two power connectors, too, (one 6-pin and one 8-pin) although under load it added a total of just 120W to our test rig's total consumption, which is comparable to an Nvidia 8800 GTX.

But while the card itself may be ungainly, you can't argue with the maths. Doubling the 3870's 320 stream processors gives the X2 a ridiculous 640 shaders to play with, with 32 texture units and 32 ROPs (raster operators). There's a whole gigabyte of dedicated RAM, too (with both GDDR3 and GDDR4 supported). As a result, where a single 3870 can't quite get the best out of modern games, the X2 romps through them.

When we ran our Crysis benchmark on an Intel Quad Extreme-based test rig at 1,600 x 1,200 with high detail, a single 3870 managed an average frame rate of 24fps. In the same test, Nvidia's 8800 GTX scored 29fps. The 3870 X2 achieved an impressive 31fps - equal to a stock 8800 Ultra.

In the Call of Juarez benchmark, the X2 did even better. At 1,600 x 1,200, again with detail set to high, it averaged a remarkable 38fps. Here, Nvidia's 8800 Ultra, working with a comparatively meagre 128 stream processors, managed just 22fps.

These are head-turning results, but sheer graphical power is only one part of the formula. Sure, some enthusiasts will pay whatever it takes to get the best performance, but if AMD is to convincingly reassert itself in the mainstream it needs to compete on price as well.

The good news is that, next to both AMD's other offerings and the competition from Nvidia, the X2 looks like good value, with launch boards from HIS and Tul coming in at £249. For comparison, an 8800 GTX can be had for around £210, while a 768MB 8800 Ultra will set you back £278.