Anyway to tell whether MoBo or PSU are faulty?

nheather · 26 Feb 2010 at 14:36

I have an annoying problem on a PC that I am about to hand down to my son.

It has a sporadic start up fault. Sometimes when you press the power up button, the fans spin and that it.

When the system starts normally, the fans spin fast, then quickly slow down and you get a bllep and the bios spalsh screen appears.

When it gets stuck the fans just come on fast - no slow down, no bleep, no bios spash screen.

Power down and on, usually results in the same until after 5 - 10 cycles it starts okay.

I figure it is either the MoBo or the PSU and would be happy to replace either - but can't work out which would be at fault.

My problem in diagnosing is

(1) Only sporadic - more often than not it starts okay

(2) No spare MoBo to try

(3) No spare PSU to try

(4) Inspected the MoBo and the capacitors look fine

Both components are fairly old

Mobo - abit IP35
PSU - Xclio 600W Great Power modular http://www.xclio.com/products/products-psu-great-550w.htm#details

Any idea what I could try to isolate the problem?

Cheers,

Nigel

Legend · 26 Feb 2010 at 15:20

Good question. I have a similar problem, where I just get a solid cursor line in the top left of the screen, before I even see the bios screen. It happens rarely but my solution would seem to indicate something is just loose, as I simply have to nudge the case and it starts up properly!

Have you tried removing RAM, or any other cards you have in there (not GPU ofcourse)? Just to rule all that stuff out.

Admiral Huddy · 26 Feb 2010 at 15:38

Testing afor a faulty mobo can be tricky as you have eliminate the other components first.

To test your PSU, give this a read:
http://www.huddysworld.co.uk/index....rking&catid=40:techie-talk-hardware&Itemid=72

panta · 26 Feb 2010 at 15:43

Test the power supply with a digital multimeter.

http://www.bfgpower.com/troubleshooting.html#DMM

Software voltage readings can be completely off, so I strongly suggest that you use a DMM to do this test.

nheather · 26 Feb 2010 at 17:18

Many thanks - I'll give that a go now and report back.

12V - 12.23V - tolerance = +1.92%
5V - 5.07V - tolerance = +1.40%
3.3V - 3.28V - tolerance = -0.61%

So they are fine at the moment - but then my computer is running fine at the moment.

I'll measure next time it fails but it is confirming my initial suspicion that it is the MoBo - I have fixed a couple of MoBos before that had bad caps - but as I said these are not showing any signs of bulging or leaks.

Cheers,

Nigel