I'm trying to boot this PC for the first time. The motherboard's RGB lighting comes on, but pressing the power button only makes the fans spin for about half a second before the system shuts down. I've checked that the power cables are connected securely and appear to be plugged into the correct sockets. The RAM is installed in the A2 and B2 slots. Could an incorrectly applied CPU thermal paste or another assembly issue be causing this? What should I check to find the problem?
3 Answers
Thermal paste usually won’t cause an instant shutdown unless the CPU cooler is missing, badly mounted, or the CPU is overheating very quickly. Check that the cooler is firmly attached, its fan is connected to the CPU_FAN header, and the CPU power connector near the top of the motherboard is installed. If the system still shuts off with a minimal setup, check the motherboard diagnostic LEDs or speaker codes for a hardware fault.
An immediate shutdown can happen if something is shorting the motherboard. Remove the board from the case and test it on the motherboard box with only the CPU, cooler, one RAM stick, and the power supply connected. Make sure there aren’t extra standoffs under the board, loose screws, or misplaced front-panel connectors. If it stays on outside the case, the problem is probably the case installation.
Start by reseating the RAM and confirming the sticks are in the motherboard’s recommended dual-channel slots, usually A2 and B2. Also unplug and reconnect the 24-pin motherboard cable, 8-pin CPU power cable, and GPU power cables until the clips fully lock. If possible, try booting with one RAM stick at a time.
The RAM is already in A2 and B2, and I believe the PSU cables are connected correctly. I’ll reseat everything and test with one stick.
How can I narrow down where the short is coming from? Testing the board outside the case sounds like a good way to isolate it.