CPU continually restarts

[Wilki29]

When I boot up my PC it starts up, but then restarts for no apparent reason. I had it up earlier and it worked fine. The only thing I changed was the CPU and fan, but I dont think that should have done any harm. If anyone has any ideas, that would be awsome. Thanks

 

[moosey]

check and make sure the HSF is mounted properly and making contact

 

[Wilki29]

I tried that and it didnt work unfortunatley

 

[Wilki29]

ok I fixed it, but now it comes up saying. "unknown flash type", and wont let me boot from a cd.