Core i3 2100 + NV GT520

[Izus]

Hi, I'm using a Linux version of Dolphin on my HTPC. During playing, I've found, that some games even for GC has a FPS drop and sound distortions.
So, which part need I upgrade first:
Intel Core i3 2100 (3.1Ghz, 3M Cache) or nVidia GT520 1Gb?

Thank you.