I have Intel Core 2 Quad Q6600 processor in my system with an Nvidia GeForce GTX 560 graphic card. I want to change my processor for better performance of my system. I use my computer mainly for gaming and the games which I play are usually games with usually heavy graphics. The PSU of my system is good to support newer processors and graphic card. I have browsed internet for various new processors. Out of many I have Intel Core i5 2500K and Intel Core i3 2120 in my sight as their specifications are good enough for heavy gaming. Before I buy any of the both processors, I would like to know how efficient they are when compared among themselves when it comes to gaming or other heavy processes. Can any experienced users share their views on the processors I have mentioned? Most probably I will overclock them for faster performance, so which processor will provide faster performance when overclocked?