Pc Won't Turn On

[KingRolo]

Okay, have father-in-law's acer mini tower which won't turn on. Had spare PSU, but still nothing. When power cable is initially plugged in, processor fan turns a few times. Any ideas?
Thanks

[KingRolo]

Using my leads which I know work. Funny how the fan turns when I plug the lead in. Cheers

[Tuvok]

Does the fan turn when you press the on/off button?

Is the processor seated correctly?

Is the thermal grease giving a good contact between the fan and processor?

Does the computer make any beeping noise? If so count them.

Take out the ram, strip by strip and turn on.

Take out all ram - if power is getting past processor to the board, you should get beeps to indicate no ram.

If its go a video card, take it out and try.

Could be that the motherboard is kaput.

[KingRolo]

The fan makes a couple of revolutions and halts only when I plug the power lead in.

Processor seated correctly, but can't see the grease unless I strip the fan and heat sink off (won't the grease then shift anyway?).

Tried removing ram. No beeps at any stage.

Tried bypassing on-off switch (no reset switch) but nothing.

No lights on motherboard.

Starting to think it is motherboard, unless I am missing something else

[Old_Geezer]

My guess is that the power supply is detecting a problem (real or otherwise) and turning off rapidly after powering up the PC.

You could try a different power supply if you have one handy. Otherwise try monitoring the output of the power supply both connected to the PC and disconnected. Try to get a feel as to whether the motherboard or something is dragging it down, or whether it is simply failing.

[Tuvok]

Sound like motherboard to me.

Do you have the manual for the motherboard - mine has a jumper that makes the usb ports powered even if the computer is not on - so if the power is on ie. for copying on my printer, my usb optical mouse is lit up.

If you have that jumper and a similar mouse, that would be a test of whether there is power going through the motherboard.

I suspect that the fan is turning just with the initial trickle of power when power is supplied to the power supply - is the fan connected directly to the power supply or does it come from the motherboard - can't remember how mine is connected.

[SlackAlice]

Case fans running? Sometimes case fans are directly powered from the PSU.

[Old_Geezer]

Sorry, I must pay more attention to the original post. I see you do have a spare power supply and have tried it already. My suspicion is that something is dragging the output down then. Try connecting all but the motherboard and see if the supply stays up. I would have suggested connecting one supply at a time but I'm concerned whether the board protects itself if one voltage is present but another not. It should, but at your own risk. Beginning to sound like a possible board upgrade scenario to me.

[KingRolo]

Very grateful to everyone's answers. It does appear to be the motherboard, and given the value of the machine and its age... an improved replacement will be suggested to the Father-in-law

[Dizmo]

I'd also suggest removing all cables to the Motherboard (except for the PSU and switch). It could be something as simple as a faulty USB port (external to internal shortage). You shouldn't see any CPU paste until you remove the processor itself. Strip everything...

[Dizmo]

Also it isn't going to look like grease. It will look like a solid compound.

[Tuvok]

If it is the motherboard, you have 2 options

1. Replace it - but bear in mind you may also need new ram, new video card, and, depending on what connections the board has eg. sata/ide, an adapter for your hard disk and cd/dvd drive. Not to mention new processor!

2. New computer - which will probably come wit Windows 8.

You will still be able to access the files on the current hard disk - you may need an adapter or external drive case.

It might be that buying the components works out cheaper that a new computer or vice versa.

[KingRolo]

Thanks for the answers... how easy is it to use the old hard drive in a new mahcine? Presumably it won't be an easy plug and go answer. Guessing drivers need updating and something in bios?