Sizing 'em up
If you haven't caught on by now, the Radeon HD 4870 X2 is, well, really frickin' fast. We'll get to the game benchmarks shortly, but we can quantify the X2's prowess in several ways. Here it is compared to the most relevant competitors and some older cards of the same class.

Those are the theoreticals. Here's how the cards measure in 3DMark's synthetic tests.

For what it's worth, I continue to be befuddled by the Gtexels/second numbers coming out of 3DMark Vantage. The units have to be off; they don't match the capabilities of the cards. We first discovered this problem and asked FutureMark about it in early June. They have been very polite about telling us several times since then that the people who might fix this problem are on vacation. (Note to self: try to get job at FutureMark.) For now, we'll continue to assume the relative performance measured here tracks well, even if the units reported are incorrect.

And the numbers look quite nice for the 4870 X2, which beats out its semi-ostensible competition in the dual GeForce GTX 260 SLI in both tests and proves to be easily the fastest "single card" anywhere in these two key metrics.

Then again, shader processing is quickly becoming the primary performance constraint in newer games. Here's how the 4870 X2 stacks up in that regard.

Yeah, uh, 2.4 teraflops will probably do you pretty well. Nothing else out there even comes close. 3DMark has some synthetic shader tests that will give us a sense of the X2's delivered shader performance.

None of the multi-GPU solutions performance particularly well in the GPU cloth and GPU particles tests, including the X2. Its additional sideport bandwidth doesn't seem to be of any help, either; two 4870 cards in CrossFire perform similarly in those two tests.

The parallax occlusion mapping and Perlin noise tests are another story altogether. The X2 is the fastest single-card config, and dual X2s are even faster than three GeForce GTX 260 cards.