I removed my AMD CPU cooler to replace the thermal paste, and afterward the computer stopped displaying anything. The fans may run, but there are no lights on my mouse or keyboard, even though the USB ports can still charge my phone. I've reseated the RAM and graphics card, checked that the CPU and socket pins appear intact, and removed the CMOS battery for a few minutes before reinstalling it. I haven't yet left the system powered off for several hours. What should I check next?
3 Answers
Inspect the CPU socket very carefully under a bright light. A bent socket pin can prevent the system from completing POST after the cooler is removed, even if the CPU itself looks fine. If the pins look normal, check both ends of the 24-pin and CPU power cables, make sure the power switch on the back of the PSU is on, and verify that the case power-switch connector hasn’t come loose.
The cooler may be mounted too tightly and applying uneven pressure to the CPU. Try loosening each mounting screw by a small, equal amount using alternating turns, then test again. Since you only unplugged the cooler’s long cable and didn’t intentionally remove the motherboard power connections, checking the socket, RAM, and cooler pressure would be a sensible order. If you’re uncomfortable working inside the system, having a repair technician inspect it is reasonable.
Start with the basics: try booting with only one RAM stick installed in the slot recommended by the motherboard layout, then test the other stick if needed. Reseat the 24-pin motherboard cable, the CPU power cable, the graphics card, and any other connections that may have been disturbed. Also confirm the power supply switch is on and the front-panel power wires are still connected.
It’s a second-hand motherboard and I don’t have the manual, but I can probably try the RAM slots one at a time. I’m not very confident about unplugging the other cables, though the CPU pins look intact.
I didn’t unplug the cooler cable while applying the thermal paste because it was long enough to leave connected. I may have a professional look at it in person.