Suddenly bad fps in all games constantly

[mattsb]

I recent built a computer and all has been running fine. I have had it roughly a month now and suddenly I can barely run any games. I've got from 950 fps in CS:S to roughly 20-30 and it's unplayable. I've monitored my temperatures and everything is around 32C. My CPU however, runs at 100% almost constantly when I try play a game. The only conclusion I can think of is my GPU not working as it should, but i have no idea how to test for issues on this or how to fix it.

My specs are as follows:
quad-Intel core I5 2500K
Geforce gtx 670
2x4GB DDR3
Windows XP SP2
Asus P8Z68-V LX

Thanks.

 

[GodlessGamer]

i can suggest the obvious, which is dust, however at the temperatures you stated i doubt that to be the problem, have you updated your drivers ? that's all i can think of dude, i had the same problem a few times, was always sorted by restarting my computer

 

[HEXiT]

100% cpu means you have a problem. open task manager and see what is taking up the processor time. then either uninstall that app/driver or process and download a clean antivirus and antimalware app like malware bytes and avira antivir.
run malware scans to m ake sure you got everything. then either replace the broken driver by downloading fresh 1s from a reputable source. run sfc /scannow from the command promt (run as admin) to repair any broken windows components. or reinstall the app if it comes on a legal disk.

 

[mattsb]

I used all the suggested methods, however I found out my speedfan software was faulty and was showing the wrong temperature. My CPU is MASSIVELY overheating even though I have changed nothing. There is no dust in the fan. I reapplied thermal paste but it's still incredibly hot after a few hours of cooling win fans still working on it. (it is roughly 90C after 2 hours cooling)

 

[MajinCry]

Hmm...Perhaps your processor has been jiggled slightly? Maybe your heatsink got dinked ever so slightly and isn't making complete contact with the CPU? Have you checked your voltages in your bios?
How did you apply the thermal paste? It should be applied as a blob on the silicon, then spread out by pressing the heatsink on it.

 

[mattsb]

I think it's an issue with my thermal paste. I am using a very old one provided by a friend and he did warn me it may not work properly. And yes I used the method above. Voltages are fine as well. I will buy some new thermal paste tomorrow and see how it goes. Thanks for the help