I upgraded my CPU and installed a large Noctua air cooler. I had to unplug the graphics card during the process, then reassembled everything. The system's lights come on and the fans spin, but the monitor shows no signal. Pressing the power button also does not shut the computer down, so I've been switching off the power strip. I already tried reseating the RAM in different slots and resetting the CMOS with a screwdriver, but neither helped. What should I check next?
4 Answers
No video does not necessarily mean the GPU is the problem. The system may be failing earlier during POST because of the CPU, RAM, socket, or motherboard. Check the motherboard’s diagnostic LEDs or POST code display if it has one. Since the CPU was replaced, confirm that it is supported by the motherboard and that the BIOS version recognizes it. Also inspect for bent socket pins, an incorrectly oriented CPU, or excessive cooler pressure.
Double-check the CPU installation and all components you handled while changing it. The alignment markers should match, the CPU should sit flat, and no socket pins or contact pads should be damaged. Reseat the RAM and try booting with only one stick installed in the motherboard’s recommended slot. Remove unnecessary USB devices and expansion cards as well, then test with the minimum hardware needed to reach POST.
Start by checking every connection that was disturbed during the upgrade. Make sure the graphics card is fully seated and that its 6- or 8-pin power cables are connected. Also verify that the motherboard’s main 24-pin ATX cable and the CPU power cable near the processor are firmly plugged in. If the graphics card is connected but the monitor cable is plugged into the motherboard, move it to the GPU’s video output unless the processor has integrated graphics.
If the power button will not shut the system down after holding it for 5–10 seconds, check that the case power-switch connector is attached to the correct motherboard header. You can also briefly disconnect the case switch and use the motherboard’s power pins to test it, if you’re comfortable doing that. Avoid cutting power at the strip except as a last resort, since abruptly removing power can cause problems while the system is running.
I held the power button down for more than 30 seconds and it still stayed on, which is why I ended up using the power strip.