PSU question

[paulbacon]

had this problem last week. I turned on the PC, and it booted up but my USB modem wasnt on. Rebooted thinking the PC was just being stupid, but it wouldnt reboot. I think its the PSU but anyone with more insight know?

The PC turns on and the fans spin, and there is a signal to the monitor but i get no picture at all. Dont get any beeping noises or anything like that to suggest a hardware failure but it doesnt try to boot into windows. The CD light remains on during this. Ive tried cleaning the inside and reseating everything, but still nothing.

One thing that leads me to suggest its the PSU is that when i plug it in but dont turn the PC on, i can hear a whistling noise coming from it. Ive heard this for a few days but assumed it was the fan, but seems it wasnt. Also once when i tried to turn on both the CD light and the USB modem light flashed. If the USB modem light went on then clearly there is power going to the USB port, so rules out a motherboard failure

Can a PSU break but still turn the PC on (to some degree)?

[Michael]

It does sound like the psu is the cause of the problems. It could also be down to a faulty ram stick/gfx card but as you mention a whistling sound coming from the psu before even turning the pc on I would start on that first as thats pretty worrying to say the least.

I presume it never used to make that sound or could it be that you just never noticed it before?

I would change it for another one asap to be on the safe side.
Don't get a nasty unbranded one from pcworld etc. Get a good branded one like an Enermax, Antec or Corsair.

Assuming you have 2 ram sticks in the pc take 1 out and try booting up again to rule out faulty memory to.

[paulbacon]

Its still under warranty so a guy is coming out with a new PSU to sort it.

Im almost certain the noise has only just started happening (about 3 days or so before the failure). When its quiet in the room its noticeable and something i would have heard before. Although i thought if the PC was turned off (but the plug still in the socket) then no power was going to it? So why does it still make the whistling noise

Faulty gfx or ram? Possible although it would still try and boot up and the motherboard would beep to let me know i would have thought? I may give it a go tho as i have 2 1gb ram sticks in at the moment.

Im currently on my old 6 year PC thats a little temprimental. Im leaving it turned on until the PC is fixed as if i turn it off it may not come back on.

[Michael]

Does the psu have a switch on it to turn it on/off? That would be why there is still some power going though it. Not all psu's have the switch mind you.

Faulty ram/gfx could be causing no picture to be displayed though it still doesn't really explain the loss power to the usb modem.

Hopefuly the guy will swap over the psu and all is back to normal so yeah you might as well leave it well alone in that case with it being under warranty.

[cliff]

Its still under warranty so a guy is coming out with a new PSU to sort it.

Im almost certain the noise has only just started happening (about 3 days or so before the failure). When its quiet in the room its noticeable and something i would have heard before. Although i thought if the PC was turned off (but the plug still in the socket) then no power was going to it? So why does it still make the whistling noise



It could be that the voltage on all the rails has dropped. The motherboard will be looking for the 12v and 5v supply. You will still have the PSU on with this condition and no monitor output.

[paulbacon]

Yeah i do have a switch on the back. Cheers guys put my mind at rest that this is the most likely cause.

Just hope i havent fried anything tho. During me trying to get it work, once i turn it on it wont turn off at all. Only way was for me to flick the PSU power switch

[julianholden30]

Def sounds like either dodgy ram or psu.
New Ram £20-30 from ebuyer - psu £15
No major operation

[paulbacon]

Was a faulty PSU in the end. Mesh just contacted me to tell me its been replaced. Shame they didnt trust me when i told them that was the fault, as they could have replaced it onsite and saved hassle at both ends