Intermittent problem turning on system?

[Dinosaur]

ASUS P2B AGP Motherboard running Windows 98 SE.

There has been an intemittent problem turning on my second system.

About 2-3 weeks ago, the system did not respond to the on/off button at the front of the tower case. It did not respond to the restart button either. When the on/off switch at the back of the tower case was turned off for a few seconds and then turned on, the system could be started using the on/off switch at the front of the case.

Today, there was a lot of trouble starting the system. I shut it down from the on/off switch at the back of the case several times before it would respond to the on/off button at the front of the case. This suggests that the problem (whatever it is) is getting worse.

The motherborad is several years old. Might this be caused by a weak CMOS battery? Might it merely be a marginal connection somewhere on the Motherboard? Could dust on the motherboard casue this type of problem?

I built the system myself several years ago and now my girl friend uses it. She is computer savy, so I am sure she did not do anything dumb.

When possible, I avoid reinventing wheels, but will open the case and check connections if nobody here has a good idea.

Thanx for any advice you might have.

[Sylvander]

Download my Diagnostic Flowcharts from here
www.erniek.eclipse.co.uk/downloads/sylvanderdiags.zip
and print them to leaf through.
They will help you narrow the focus upon the likely causes and areas on which to concentrate.

If the PC appears dead you will be taken to the SYSTEM chart.
If you have an ATX board then special expertise is required to test the PSU.

If it's a failure to complete the POST that's a different matter.
I had an intermittent failure to POST due to an old, noisy, failing fan which I suspect was causing the PSU to short.
When I replaced the fan the problem went and has not returned.

[Budfred]

It sounds like it could be a simple matter of the switch going bad. I would certainly blow out the dust to make sure it isn't just dust interfering with a good connection being made. You can check if it is the switch by momentarily shorting the pins that the switch plugs into on the motherboard. If it starts right up, it is likely to be the switch that needs to be replaced. If it doesn't, it is more likely to be the power supply and I would try another one if you have one handy. It doesn't sound like a motherboard problem....

[Dinosaur]

BudFred & Sylvander: Thanx! You gave me some thoughts to work on.

I cannot do anything now, because the system is running and my girl friend is using it.

Thanx, again.

[Dinosaur]

It was the power supply.

Thanx for your help!

[Budfred]

Thanks for the update....:)

[Dinosaur]

Sylvander: After getting a new power supply which fixed the problem, I downloaded your diagnostic flowchart.

It looks great!! I am keeping a copy on my system.

[Sylvander]

They help eliminate areas unlikely to be the cause and narrow the focus on the likely cause[s]:)

I often refer to them myself to remind me of what I should be concentrating upon:cool:

I've made improvements over time, but I wish, I wish I understood more:(