In the Lab: Gordon Mah Ung Cross-Examines CrossFire


In the Lab: Gordon Mah Ung Cross-Examines CrossFire

AMD's Radeon HD 3870 X in quad mode scales well for having four GPUs.


I’ve been skeptical of multi multi-GPU support since the days of Nvidia’s original Quad SLI. Back then, bad drivers, a lack of game support, and 30-inch panels that cost a month’s pay made the prospect unpalatable.

So when AMD sent us an Alienware ALX system decked out with four GPUs, I didn’t expect much. But the dual Radeon HD 3870 X2s in this rig performed pretty damn well. In a system sporting a 3GHz Core 2 Extreme QX6850 overclocked to 4GHz, an Asus X38 board, DDR3/1800 RAM, and Windows Vista, the double double-barreled 3870 X2s’ performance at ultra-high resolutions shocked the hell out of me. In 3DMark06, Call of Duty 4, and Unreal 3, I saw a roughly 40 percent increase in frame rates going from one Radeon HD 3870 X2 to two.

At lower resolutions, closer to reality, the four Radeon GPUs didn’t up the ante quite as much at 1900x1200, but there was still a healthy 20 percent boost in COD4 and UT3. That’s probably not worth filling that second slot, but at least the setup offers decent scaling. The Radeon HD 3870 X2 ain’t perfect, though. Driver problems initially plagued our preview of the cards, so our assessment is that this quad-GPU solution isn’t quite ready for prime time.

It’s not much of a secret that Nvidia has its own second-gen Quad SLI coming out. It will use two new dual-GPU cards dubbed GeForce 9800 X2. It’s obviously too early to say which will be faster, but the quad Radeon HD 3870 X2 at least presents a respectable dual-card solution for folks who want to build a high-res gaming box using an Intel X38 or even X48 chipset.


CrossfireX Performance
  CrossFireX Single Card % Difference
2560x1600, DX9
21,050.0 12,889.0 38.8%
3DMark06 HDR1 Canyon Flight 2560x1600, DX9 (fps) 52.7 30.0 43.1%
3DMark06 HDR2 Deep Freeze 2560x1600, DX9 (fps) 51.3 26.0 49.3%
Call of Duty 4 2560x1600, DX9 (fps) 93.0 73.0 21.5%
Unreal 3 CTF-OmicronDawn_Bot 2560x1600, DX10 (fps) 118.0 65.6 44.4%
Unreal 3 CTF-OmicronDawn_Bot 2560x1600, DX9 (fps) 120.3 68.5 43.1%


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