Member Avatar for burgercho

I'm dealing with an Optiplex GX280 that was randomly freezing and then randomly shutting down. After a little bit it stopped turning on altogether and the only things that would happen were that I would get a yellow light and I could here the CPU fan speeding up to it's max speed. After I reset CMOS it started up normally again but after a bit started randomly freezing again. I'm rather puzzled. Could it be the PSU? and if so why would resetting CMOS make it start up again?

Other info: Apparently there is a common problem with capacitors on motherboards of the GX280 (see this thread) but if that were the case resetting CMOS wouldn't have fixed it, so I'm leaning toward the PSU, but then why would resetting CMOS fix it and why would fan speed up?

Any help is apreciated, thanks.

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  • Latest Post Latest Post by markanderson_1

Dani AI

Generated

Quick summary of likely causes and a practical test plan.

The symptoms you describe — random freezes, full shutoffs, then later a solid amber LED and the CPU fan revving to max after a failed start — point at an intermittent power-delivery problem or a failing motherboard power subsystem, not a pure software/OS issue. A CMOS clear can temporarily allow a system to POST by resetting BIOS timers, fan-control thresholds or clearing a latched fault; that isn’t proof the board is healthy, only that the firmware state changed long enough for a boot attempt.

Stepwise isolation (low risk, high value)

  • Remove everything nonessential (cards, extra drives, front USB devices) and try a minimal bench boot with one stick of RAM and onboard video if available — this rules out peripherals. This follows ’s intuition but with a strict minimal-boot order.
  • If minimal boot fails, check DC rails from the PSU with a multimeter or a cheap PSU-tester: acceptable ranges are roughly +12V = 11.4–12.6 V, +5V = 4.75–5.25 V, +3.3V = 3.135–3.465 V, and +5VSB ≈ 5 V. If any rail sags under load or +5VSB is missing/low, the PSU is the prime suspect. Do the measurement only if comfortable and after reading safety notes below.
  • If the PSU is very hot to the touch (as observed) or you smell burnt electronics, replace/stop using it.

Inspect the hardware

  • Look for bulging/leaking electrolytic caps on both the motherboard (especially around the CPU VRM) and inside the PSU. Bulging tops or brown residue are reliable fail signs. Also check for scorch marks, cracked solder joints, or loose CPU cooler mounts. Fans pegged at full speed can happen when the board’s fan-control PWM signal or temperature sensor is absent or out of range.

What to try next

  • Swap in a known-good, compatible PSU (watch for Dell proprietary SFF connectors). If that clears the problem the PSU was the culprit. If not, the board’s VRM or caps are likely failing; recapping or replacing the motherboard is the next practical move.
  • Safety and practicality: disconnect mains before opening the PSU (do not open a mains PSU unless you know what you’re doing), use ESD precautions when handling board and CPU, and if unsure, have a local repair shop do the electrical tests and any recapping.
Member Avatar for dwizzle40

I would think that it is most likely the PSU as you suspect. I am actually working on an Optiplex GX150 with the same problem right now. I found documentation on the Dell support website that stated if the power light on the front of the case was a solid amber color that it means there is an internal power problem. Try using another PSU to see if it continues to happen. As for resetting the CMOS haveing an effect on the machine; I don't know computers can be funny things, it could just be a coincidence and the PSU is having an intermittent issue (which are the most difficult issues to diagnose).

Member Avatar for saveone12

Did u unhook everthing (not the power supply ) and then try it ?

Member Avatar for markanderson_1

I did intstall a VC to the system. It worked well for a long time and I had a Sound card installed too. Now I have the exact same symptoms - All pointing too overheating - The power supply is hot to the touch. I am going to order PS replacement and if that does not work I am going to part it out and buy a Mini Mac for the 1st time.

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