So when we move from two GTX 260's to GTX 280's we see that the extra shader processors could use a faster processor. We start to see the advantage of the faster processor here.

This really can only mean one thing for 3-way SLI though, the Core i7 is gonna kick big-ass butt. Let's have a peek.

NVIDIA GeForce GTX 280 3-way SLI (3 GPUs - 3 Cards)

There we go, so the general consensus here is that with the faster GPU setups starting at say 2x GeForce GTX 260 in SLI or two Radeon 4870 in Crossfire you'll start running into CPU bottlenecks with a fairly modern PC.

After such SLI setups, faster processors are bound to make a difference, a very big difference.

Multi-GPU scaling overview on X58 Core i7 965 system

So here's a nice overview of a dozen or so cards on the new X58 platform. Can you imagine what would happen if we started to compare say a single Radeon HD 4870 to QuadFire? I mean it's sick how much performance you are staring at, 4870 X2 in CrossfireX @ 1280x1024 for example poops out nearly 300 frames per second at the best image quality settings.

And it's still pushing near 150 FPS at 2560x1600 -- OMG !!