A few days ago my computer turned itself off and would not turn itself on. I diagnosed (what I believed to be the problem) as the motherboard. I picked up a new motherboard that seemed like it would work (the 970 Extreme3) and basically just switched over all all the components to the new motherboard. The computer started just fine, but after about an hour or two shut off. I checked the CPU temp to see if it was overheating and it was at a solid 115 C. I left the computer for awhile and came back and watched the temp steadily climb from 40 C to about 100 before I decided to turn it off before it did itself anymore damage.
I was wondering what could be causing my CPU to overheat? Was the CPU in the first place that ruined my first motherboard?
I'm guessing that when you swapped motherboards you didn't replace the thermal paste on the CPU. This is a big no-no for reasons you've just discovered. Remove your heatsink, clean off the old thermal paste with rubbing alcohol and apply fresh paste. There are tons of guides around on how to properly apply it.
Also, stop using your computer immediately. Temperatures that high can literally destroy processors.
Thank you for your replies, After the cpu overheated once I didn't turn it back on because I know it can damage things. I am pretty sure I need to get more thermal paste and reapply it because I did not do that when I replaced the motherboard. I will do this first thing tomorrow!
Yep, not reapplying paste will do it. The stuff bakes on when it first heats up, so when you pull the heatsink off it can't spread out to fill the tiny imperfections in the heatsink and die anymore. It turns into an insulator rather than a conductor.