I recently assembled a PC from some spare parts I had around, but I'm having a tough time with the motherboard and CPU. Here's the deal: I got the motherboard and CPU from a friend, and when I turn on the power, the motherboard's LED strips flash bright white momentarily before going dark. I tried shorting the power pins to see if that made a difference—fans spin, the GPU gets power, and the RAM and NVMe appear to work fine. However, the CPU stays completely cold, which really surprises me since everything else seems to function properly.
The specs include a B550 Aorus Elite V2 motherboard, an R3 4100 CPU, a random NVMe drive, and 2x4 RAM sticks with a Quadro 4000 GPU. I've confirmed that my PSU works, as I tested it separately.
What I've done so far:
- Swapped out the CPU for my R5 5600X, but no change.
- Reseated the RAM and tried using each stick individually.
- Used Q-Flash+ to update the BIOS without issue (it doesn't need the CPU for this).
- Cleaned everything with ISO and visually checked components.
I'm running out of ideas; the CPU remains cold, and while USB devices are recognized (which allowed me to update the BIOS), the system refuses to boot. Any suggestions would be greatly appreciated!
3 Answers
First off, double-check the 8-pin CPU power cable—you might have it misconnected or it's loose. It should connect to the CPU/EPS and not the PCIe. Also, inspect the CPU socket pins on the motherboard to ensure none are bent. After that, recheck the RAM again, including trying one stick at a time in different slots. If none of this works, consider doing a CMOS reset. Does your motherboard have any debug lights to help diagnose the issue? Let me know how it goes!
From what you're describing, does nothing really turn on, or do the fans move or LEDs blink before cutting off?
Have you tried using PCPartPicker.com to check if all your components are compatible? Sometimes, incompatibility can cause booting issues, even if everything looks good physically.
All the fans I connect spin like normal, including the CPU fan. Everything powers on briefly and heats up, but the CPU itself remains unresponsive. I see a LED behind the motherboard heatsink that blinks briefly, but then it cuts out. It can blink white, yellow, or orange before shutting off.