Help me find the BOTTLENECK in an older gaming rig

[Tron87]

I have been very happy with my rig for a few years now. I was just recently trying to play Bioshock Infinite and noticed that the frame-rate was horrendous. On high/ultra I was getting 15 FPS and when I put it on low settings I only increased to 20 FPS.

So here are the specs.

GigaByte P35-DS3L Mobo
Nvidia EVGA GTX275 (896 onboard RAM and 240 CUDAs)
4Gb Patriot DDR2 6400
Intel Core2Quad 6600 CPU (Overclocked to 3.2Ghz)
90G SSD
700G HDD

Judging by some resource usage stats during gameplay I think that bottleneck is GPU but I am also worried about the amount of RAM being a bit low for modern games.

 

[Tron87]

Anyone? I hoped to have a solution in time for black Friday sales.

 

[stormworm]

It's gpu. Most games will run fine with stronger GPU.