Sapphire Radeon 4870 X2

For a long time, we’ve considered videocards that sport two GPUs second-class citizens. They have all the problems of multi-card solutions—namely application incompatibilities and no multi-monitor support—but fail to perform as well as dual-card solutions, since multi-GPU cards usually use slower midrange GPUs. That’s finally changed with the new RV770-powered Radeon 4870 X2, which mounts two of ATI’s fastest GPUs on a single card, without sacrificing power-user features like multi-mon support.

The 4870 X2 is essentially two Radeon 4870 HD cards running in CrossFire mode packed onto a single board: The X2 has the same GPUs, the same 800 shader cores running at the same 750MHz core clock, and the same GDDR5 memory running at 900MHz. But, there is one difference. The single-GPU 4870 includes 512MB of memory, while the X2 has a whopping 2GB. However, the memory is duplicated between the two GPUs, so the effective frame buffer for the card is just 1GB. The X2 also features a high-speed PCI Express interconnect between the two GPUs, which should, theoretically, boost the efficiency of the shared GPUs. However, in our tests, we didn’t see an appreciable performance difference between a traditional CrossFire solution and the X2.

The 4870 X2 outperformed the previous single-card performance champ in most of our benchmarks, delivering playable frame rates at 1920x1200 and 2560x1600 in nearly every game we tested. Naturally, the exception remains Crysis, which, at its highest quality settings, punishes nearly every system we’ve tested. We’re slightly concerned about the accuracy of our Crysis benchmarks; the ATI card seemed to render far-off textures at a higher resolution than the Nvidia card. We’ll test further and report back next month.

As always with high-end cards, if you’re running a low-resolution display—pretty much anything below 1920x1200—you won’t be able to harness the full power of this card. At lower resolutions, the 4870 X2 performs exactly the same as the single-GPU 4870. For anyone running a high-res panel, the X2 truly kicks ass.
This card is a significant upgrade if your GPU doesn’t support DirectX 10—and is much better than some last-gen cards that do. If you’ve been waiting to make the jump to DX10, now’s the time to shell out the bucks—you won’t see a better performer for quite a while.

Benchmarks

	Radeon 4870X2	GeForce GTX 280
Crysis 4X AA/Very High (fps)	16.3	17.4
Crysis noAA/Very High (fps)	21.6	20.8
Call of Duty (fps)	81.8	68.3
Vantage Game 1 (fps)	10.8	17.6
Vantage Game 2 (fps)	13.0	12.1
UT3 (fps)	131.0	124
Grid (fps)	35.9	46.0

Best scores are bolded. Benchmarks are run on an Intel Core 2 Quad Q9770 Extreme, with 4GB of memory running Windows Vista. All tests are run at 1920x1200, with 4x AA and 8x anisotropic filtering, unless otherwise noted.