PC won't start - power supply?

  squ1rrel 10:45 18 Jun 08
Locked

My PC has been working fine for nearly 2 years with no h/w changes but now won't start. When I press the power-on button it starts to power up normally: lights and fans start and disk & CD lights flash but then after 5 seconds it powers off (mobo led remains on). It is consistently 5 seconds from power on to power off.

The case is an Antec Aria sff with non-standard shape 300W power supply.

Does this sound like the power supply failing or something else?

thanks

  Technotiger 10:47 18 Jun 08

Yep, sounds like it. I would advise a more powerful PSU anyway.

  Les28 18:18 18 Jun 08

CPU heatsink fan definitely spinning OK ? Small form factor can possibly have overheating problems.

  squ1rrel 23:11 18 Jun 08

Yes - CPU fan is fine.

  C3 04:20 19 Jun 08

Strip your machine down.

Disconnect Hard Drives, Floppy Drive, CD Drives completely. That means power cables and IDE/SATA cables.

Essentially the only power cables that should be connected are the main motherboard power and the processor power (if you have this port, most modern MoBos do).

Try and turn the PC on.

If the same thing happens, see if you can get another power supply from somewhere. If you have another PC , check the connections on the power supply are the same, remove the power supply from the other PC and attach the motherboard and processor power cables to the broken PC.

Try the power again. If it switches on, then this shows that it is quite possible the original power supply is faulty. If the same thing happens again, then I would say it is a motherboard or processor fault.

  squ1rrel 23:21 22 Jun 08

Ok... I've stripped the PC right back as C3 suggests to mobo, cpu & memory. As before, it shuts down after 5 seconds.

I also have another working PC that I have combined this with:
1) first system (stripped down) with power supply of second system => powers down after 5 seconds.
2) second system with power supply of first system => starts ok.
So the problem is not with the original power supply.

However, in the original configuration (first system with its normal power supply), there is a high-pitched whine from the power supply as soon as the mains is switched on. For the 5 seconds of power up, the whine goes away but when it powers off, the whine returns but is louder than before the power up attempt.

When the first power supply is connected to the second system, there is no whine. And when the second power supply is connected to the first system, there is no whine (but powers off after 5 seconds).

So the results of the tests suggest it is not the power supply, but maybe a mobo problem. But how would that account for the power supply whine?

  woodchip 23:32 22 Jun 08

Fan in PSU may have stopped, Bet you have not checked that one

  squ1rrel 10:14 23 Jun 08

Woodchip - The fan in the PSU spins normally.

  Ditch999 11:43 23 Jun 08

Sounds like something in the original system is drawing too much power and as there is only the mobo, ram and cpu running it may well be the start of mobo failure.
You could try different memory and a different cpu if you have them, or only one stick of memory in different slots to rule those items out.

  grapesoda 11:31 29 Jul 08

mine too won't start. it's been dead for less than 24 hours now. after 5 seconds of working it shuts down, then now it won't start but the fan is working.

it made those bios beep codes but i don't understand beep codes... i think it's 6 beeps.

i had my power supply for 6 years now.

i hope it's just the power supply that needs changing...

  woodchip 11:37 29 Jul 08

Remove the Heatsink, clear paste from top of CPU then use some fresh Thermal compound as it sounds like the CPU is switching off to prevent damage.

PS Clean all the muck out of the sink

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