Bottlenecking is a game-dependent phenomenon. But as the Tom's low-end builds pairing pentiums with 7970s have shown, most games are far more dependent on the video card than on the processor. I think really the question is more like this: do you have a limited amount of money now that you can split between video card and processor/mobo upgrades, or are you just planning on buying a new video card now? If the latter, get the 7870. If the former, then you have to look at specific games and see how CPU vs GPU-dependent they are. But remember: you can always keep your 7870 and upgrade the CPU later. It'll be a strong card for a few years.