My CPU temperatures were running high, so I removed the cooler, cleaned the CPU and cooler, applied new thermal paste, and reinstalled everything. Since then, the computer powers on and most fans spin, but there is no display or POST. The GPU fans do not spin, and my RAM's RGB no longer lights up during startup even though it worked before. I had to remove the RAM temporarily to make room while working, but I reseated it afterward. The cables appear to be connected correctly.
I've already tried reseating the RAM and CPU cooler, loosening the cooler screws, reseating the CPU, and removing the CMOS battery. What else should I check to figure out why the system is no longer displaying anything?
3 Answers
Start by checking the CPU and motherboard socket carefully under good lighting. Look for bent or damaged pins, debris, scratches, or discoloration on the contacts. The CPU should sit flat in the socket before the locking mechanism is engaged. Also confirm that the motherboard's 24-pin power connector and CPU power connector are fully seated, since one of them may have been loosened while working around the cooler.
Since the issue began immediately after removing the cooler, inspect the CPU installation and mounting pressure again. Make sure no paste got into the socket, the CPU is oriented correctly, and the cooler isn't tightened unevenly or excessively. Try booting with only one RAM stick installed in the motherboard's recommended slot, with the monitor connected to the correct video output. Clear CMOS using the motherboard's documented procedure rather than relying only on removing the battery.
A loose power connection is a strong possibility. Unplug the PC, then disconnect and firmly reconnect the motherboard power cables, CPU power cable, GPU power cable, and any relevant PSU-side cables. Inspect the motherboard for accidental damage as well. If the board has diagnostic LEDs or a speaker, check which component it reports during startup. GPU fans often remain stopped at idle, so that alone doesn't necessarily indicate a problem, but the missing display and RAM lighting suggest the system may not be completing POST.
I only removed the cooler, cleaned the CPU and cooler, reapplied the paste, and reinstalled everything. I didn't intentionally touch anything else, but I did remove the RAM temporarily for extra space. After putting it back, the system still wouldn't POST.