I just installed a GTX 660 SC in my computer my CPU is a Intel i-5 2320. As soon as I installed my graphics card i noticed that i was getting worse frame rates and lag on videos it toke a month for me to notice but by CPU temps have been going through the roof and I don't know why.
If that is the case, try to reinstall the proc cooler (re-apply the thermal paste) or even try to buy a non-stock cooler.
Control if the fan is running, air flow is working fine, etc.
Perhaps you can still save your proc.
 I would try to fix the cooling stuffs first before trying to play games with it again