Not really. All it takes is a power spike and the PSU stops working properly.
My gf had the same problem, 10~15 fps at 640x480 low settings and 1280x1024 with the game maxed out.
I switched out her 600w PSU for a 350w one we had laying around and we got good performance again.
My main concern here is that in my case, we had that faulty psu running for a long time and when it decided to die, it took a sound card and 2 ddr2 memories with it.
Just try a different PSU, takes 10 minutes to switch it and can't hurt the OP to try
