EVGA 680i SLI

i will suggest you

Core 2 Quad Q9550,

Core 2 Quad Q9550S,

Core 2 Quad Q9450.

You already have the best chip for that chipset and board. I know because I used to have that board. Your chip is a Kentfield Q6600 chip. You can not put a newer Yorkfield core Quad chip on that board because the microcode for the EVGA 680i SLI will not support it. Believe me I found out the hard way. The next EVGA motherboard that supports a Yorkfield and higher is the 790i SLI board but even those are getting long on the tooth and a waste since the X58 SLI boards came out.

That being said, your board and chip are a great combo. 2.66Ghz is VERY slow speed for the Q6600. This chip with a good tower air cooler will easily do 3.6Ghz to 3.8Ghz with none or very little voltage modifications. This is the sweet spot for great performance, good heat management and stability. You Do Not need a new chip or board. You are better off spending your money on a fast Video card.

Yeah i tried to OC but everytime i do it my pc crashes when playing games.. i followed this handy How to... i did everything on there but still pc not stable

http://forums.hexus.net/hexus-hard [...] iller.html

yeah every setup oc's different. best way is to start slow. increase the fsb by 5mhz at a time. after pc becomes unstable then you know to increase cpu voltage/ dimm voltage. Nothing is set in stone. Thats the fun/pain of overclocking. you really have play with it sometimes. Post your hardware specs and bios settings on here and I'm sure someone will turn you in the right direction.