At that resolution you do NOT need a stronger processor . What you need is a stronger graphics card .
You may be right, but here's a few things:
I get a constant 30 FPS in, for example, Starcraft 2. I was getting this frame rate on my 20" monitor at 1600x900. After further overclocking the card, I didn't see any jump in performance either. I just feel like something is holding the system back, and I'm going to guess it's the motherboard.
Another thought, would the processor possibly not be getting sufficient power?