damric :
lol no. Don't listen to these clowns.
You are going to have the same FPS dips (minimum FPS) in clogged areas of the game regardless of what GPU you choose.
The difference is that with a higher end GPU you will be able to push higher detail settings, more resolution, higher average FPS, and higher maximum FPS. So even with a Phenom II, your game will look better with a more powerful GPU than a weaker one.
With all due respect, maximum FPS is irrelevant, it's minimum that matters. My framerate can fluctuate between 120 fps and 50 fps in Skyrim. I don't go around telling people I run it at 120 fps, because that would be misleading and the fact it occasionally gets that high isn't important.
For example, my Phenom II hits 100% in some parts of Far Cry 3. In those moments, the framerate dips to 35-40 fps. Having a stronger video card then would be pointless in FC3, because I'd keep dipping down to 35-40 fps each time my CPU maxed. A stronger video card would still raise my max FPS, but that wouldn't matter because the dips to 35 would still ruin it comparatively, so spending more than $200 on a video card in my case would have been mostly a waste of money in that game.
That's how bottlenecks work. They're not exactly the game-killing bogeyman people seem to fear, but they can really throw off the whole "bang for your buck" system of buying hardware.
We're trying to pick the GPU that would be the most efficient use of resources with a 980 here, not what would get his max fps higher at any cost. Trying to push his max FPS too far above his minimum isn't worth extra money.