Member Avatar for misterwise

Hi
This is my first post and I have a a problem that is driving me crazy.
My computer suddenly stopped booting. The power gets to the machine but nothing else. No POST just dead. I have replaced the PSU thinking this was the problem (It works ok). The hard drive is ok and boots on another machine.
I have taken out the graphics, card and sound card to see if this was causing the problem. I have taken out the ram one chip at a time too, but nothing seems to work. I suspect it may be a faulty CPU but have not way of checking this.
Any advice will be gratefully received.
Joe

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As suggests, when the box takes power but gives no POST the fault is most often the motherboard or a component the board depends on. The following targeted checks will help pin it down without repeating diagnostics already tried in the thread.

Try these steps in order (one change at a time):

  • Fit a POST speaker (small piezo) to the front-panel header and power on. No beeps is a useful clue; audible beep patterns point to CPU/DRAM/VGA issues.
  • Breadboard the system on a non-conductive surface: only PSU, motherboard, CPU (with cooler), one known-good RAM stick in the primary slot, and a video card only if the board lacks integrated video. Disconnect all drives and add-on cards.
  • Confirm the 24/20-pin and 4/8-pin CPU power connectors are fully seated. Short the power-switch pins on the panel header with a screwdriver to rule out a failed front-panel switch.
  • Clear CMOS (jumper or remove battery for a few minutes) and reseat RAM and CPU cooler. Inspect the board closely for bulging/leaking capacitors, burn marks, or bent socket pins. Verify the CPU fan spins at power-up.
  • If possible, test with a known-good PSU and a known-good CPU or test the suspect CPU in another compatible board. If you lack spare parts, a local repair shop can do component swaps quickly.

A working POST speaker or an onboard POST-code LED will narrow things fast; without those, “no activity” usually points to a failed motherboard or CPU. Handle the CPU carefully (ESD precautions) and document symptoms (fan behavior, LEDs, smells) before part swaps. For background on POST and beep codes see the Power-on self-test overview (Wikipedia) (https://en.wikipedia.org/wiki/Power-on_self-test).

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Member Avatar for alc6379

If you're looking at a bare-bones setup, with just PSU, mobo, and CPU, and we know the PSU is good, I'd suspect that motherboard. What indicators tell us power is getting to it?

Member Avatar for misterwise

If you're looking at a bare-bones setup, with just PSU, mobo, and CPU, and we know the PSU is good, I'd suspect that motherboard. What indicators tell us power is getting to it?

Hi,
Thanks for this. Not sure if power is getting to the motherboard but the pc 'powers up' ok there is just no activity. Didn't mention before that the pc came with a pentium 4 Prescott chip. I have recently installed an ATI Saphire X800 GTO graphics card and suspect that the chip has overheated as I've learned that this particular chip is prone to overheating especially when a high- end graphics card is installed.

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