I moved my PC into a different case after the old one was damaged. I reconnected the motherboard, CPU, graphics card, case buttons, and other main components, then tested it before fully finishing the build. The fans spin and the lights come on, but there is no display. The motherboard's diagnostic indicator lights also stay off. I also reapplied thermal paste to the CPU during the rebuild. What should I check?
1 Answer
Double-check the 8-pin CPU power connector near the top-left of the motherboard. It’s easy to miss during a case swap. The fans can still spin with only the 24-pin motherboard cable connected, but the system usually won’t boot without the CPU power cable. Also verify that the display cable is connected to the graphics card rather than the motherboard, and consider testing the board outside the case in case a misplaced standoff is causing a short.

I checked the CPU power connector and the 24-pin cable several times. The power supply doesn’t have the extra 4-pin connector used for overclocking, but the 8-pin CPU connector is connected.