Member Avatar for drblbaqker

Has anyone ever encounterd this before?

One of my computers will not power up. The CPU fan will "wiggle" when the power comes on but nothing else.

It seemed like it was definitely a power supply problem. NOPE! I tried a new power supply and it had the same results. I also tried the PS with all devices disconnected and had the same results.

System was working fine, began acting "funny", froze and then would not power up.

Thanks for any suggestions.

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  • Latest Post Latest Post by alc6379

Dani AI

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Quick note tying the thread together and a stepwise way to narrow this down beyond the CMOS/jumper and RAM checks already suggested by , and .

Start with the case wiring and bench test

  • Confirm the front-panel power switch and its wires. Disconnect the two power-switch leads at the motherboard and test the switch with a meter, or briefly short the two power pins on the front-panel header (consult the manual first). This rules out a flaky switch or broken front‑panel wiring.
  • Move the board out of the case for a bench test on a nonconductive surface, disconnect all extras and front-panel connectors, and try to power it with the minimum needed parts. That rules out standoffs or a short to the chassis.

Check for visible board/VRM faults

  • Look closely for bulging or leaking electrolytic capacitors (common failure mode in older boards), burned or discolored areas, or missing/broken components near the CPU VRMs. A blown VRM or shorted MOSFET can allow a fan twitch but prevent proper startup.

Verify PSU control signals safely

  • If comfortable using a meter, check the ATX control lines: the green PS_ON lead is pulled low by the motherboard to start the supply; the gray PWR_OK line goes high only once rails are stable. Force the PSU on (paperclip test) only for testing, and then measure the 3.3V/5V/12V rails and the PWR_OK signal. If the PSU behaves correctly when forced on but the board still won’t start when connected normally, the board’s power-control circuitry is suspect.

Listen for POST/beep codes and document results

  • Attach a small system speaker. Beep codes (or lack of them) give quick clues: no beeps at all with speaker attached plus no POST LEDs usually points toward a power/VRM or CPU failure.

Safety and next steps

  • Work with mains power disconnected when changing connectors. If the visual inspection and the bench/PSU signal checks point to VRM damage or no PWR_OK from the motherboard, the practical next move is repair (cap/MOSFET replacement) or board swap. If uncertain, capture photos of the area around the CPU/VRMs and POST header and seek a tech to avoid further damage.

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Member Avatar for Catweazle

You could try removing the CMOS battery (with the power disconnected of course) for a few minutes then replacing it. doing so will reset CMOS, and may enable the system to boot up again.

But it sounds suspiciously like a situation where the motherboard has malfunctioned, or where the processor has overheated and is no longer operable.

Member Avatar for tornshadow

It is either a problem with a setting in the bios or something with your motherboard. I would go with Catweazle and reset the cmos. There should be a jumper next to the battery - just move it to the next pin and move it back. That will reset it. If that doesn't work...look for a new motherboard.

Member Avatar for Catweazle

Do NOT alter motherboard jumpers without first confirming in the motherboard manual that the jumper is the correct one. CMOS reset jumpers are NOT always adjacent to the battery!

Member Avatar for alc6379

Also, swap the RAM out with known good RAM. I've had systems exhibit the exact same behaviour with el-cheapo, or failed, or both(!) RAM.

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