So out of curiosity I decided to check if my 3.8GHZ overclock was stable on my i7 920. I ran Prime 95 and my pc crashed within 20 mintues. I decided to go into the bios and raise the vcore just a bit. I ran prime 95 for about 4 hours with a stable overclock, however, the temps reached a maximum of 100 C! The next day I was browsing through the web when my pc suddenly froze. No BSOD or anything, just a freeze. I shut down the pc and turned it on again. No image, bios, or post beep. I decided to hit the cmos reset button and now it just goes into an endless loop of restarting itself. I get the codes f3,f6,68 on my motherboard (X58 SLI LE). How can I tell whether it's the cpu, or motherboard that failed on me?

After looking through reviews on OCing my CPU, I've seen multiple advisories not to use Prime95 anymore for stability testing as it pushes the CPU too hard that real world usage won't really ever do. They have others out there to use like Realbench, AIDA64, and Intel Extreme Tuning Utility, BurnInTest.

Did you try pulling the plug, remove the 3v battery and hit the clear CMOS for 30 seconds. Install battery , plug it in and see if it will post?

manny8127
When i unplug everything I just get a code ff. No beeps.

Everything? Or do you mean only the components described by HudsonH for each test? 

Try taking cpu out completely and reinstall it. Another little trick is to stick it in a ziplock bag and put in freezer for a couple hours. I brought back a 980x that I thought was smoked like this.