Within a couple of hours after replacing my CPU cooler, my system froze on three separate occasions. No sound. No response from mouse or keyboard. Monitors kept showing a frozen image. On one of these occasions I waited a couple of minutes before resetting, but it stayed frozen. The freezes were sudden. No graphical glitches. No BSOD. Nothing in the event viewer, as far as I can tell. On two of these occasions I had HWMonitor visible, and no temperature was above 60°C. This happened two days ago and I had no freezes yesterday, nor so far today. Outside of those three freezes, the system is working just fine. I wasn't doing anything in particular when the freezes occurred that I haven't done since without issue. While replacing the cooler, I unseated the CPU to more easily clean it around the sides. I was careful not to touch or damage the pins, but could this potentially have something to do with the problem? I was surprised the BIOS detected a hardware change on startup. I'm at a loss to know how to diagnose this problem and the worry of it happening again and not knowing how to prevent it is eating me up. I could go into more detail about several of the circumstances, but since I have no idea what's causing this problem I don't know what would be relevant. If anyone could point me in the right direction or has any idea of what might be going on, I'd be grateful.