At first glance, AMD's new Radeon HD 3870 X2 graphics card is nothing more than a pair of Radeon HD 3870 GPUs crammed onto a single video card and running in Crossfire dual rendering mode. PC Plus magazine has been the first to independently test the Radeon HD 3870 X2.

Indeed, AMD itself concedes that in terms of multi-GPU performance scaling, it has no advantage over a pair of individual cards running together courtesy of Crossfire.

Good news for AMD

But the Radeon HD 3800 series of graphics chips has been a ray of sunshine in an otherwise gloomy year for AMD. Last spring its first effort at a DirectX 10 class GPU, the Radeon HD 2900, failed to impress. More recently the company has been struggling thanks to the late arrival, mediocre performance and buggy circuitry of its new quad-core CPUs.

You could say AMD has been in desperate need of a good news story. The X2 is most of the way there.

The 3870 X2 is a powerful beast (it sucks 368 watts under load), but also a somewhat flawed one thanks to that Crossfire technology. Historically, Crossfire's been unreliable and far too reliant on game specific profiles built into the driver. Without the latter, multi-GPU fails to outperform single-GPU cards, and that's exactly what happened in our Call of Duty 4 test.

Crunching the numbers

The Radeon HD 3870 X2 outperformed an Nvidia GeForce 8800 GTX running Half Life 2: Episode 2 (2,560 x 1,600 pixels, x4 anti-aliasing, x8 anisotropic filtering) and Hellgate London (same setup), with frame rates per second of 50 to 43 and 76-60 respectively. But the 8800 GTX proved faster handling Call of Duty 4. Albeit by a small 28-26fps margin.

On the other hand, we have to admit that the 3870 X2 is a blindingly quick card. 3DMark 06 pegs it at a lofty 17,390, significantly quicker as an all-rounder than Nvidia's GeForce 8800 GTX, a previously peerless performer with a 3DMark 06 score of 13,014.

We had feared the Radeon HD 3870 X2's 256-bit memory bus and 512MB of graphics memory (per GPU) might not be enough for huge pixel grids like 2,560 x 1,600. But no. The 3870 X2 maintains a competitive advantage throughout.

The complete, in-depth lab report can be found in issue 266 of PC Plus, on sale 12th February 2008, and online shortly after.