Power or Mobo Problem?

[JRP1414]

Hi guys,

I've got a problem that I'm stuck with and could really do with your help .....
here goes!:

It started a few weeks ago ... every time I switched on my computer using the switch at the rear of the PSU and pressed the case power-button, the computer would attempt to boot up, make a loud 'click' and re-start. The LED on the motherboard would light up fine, fans would run briefly, etc but it just would not kick in. It would do this around 8-10 times before it properly booted up. Once booted, every thing would run fine until shut-down.

I found out that if I left the PSU switch on permanently, the computer would boot-up first time every time after pressing the case power-button. However, whilst out, my Dad switched off the mains and then it would not boot up at all.

I assumed it to be a PSU problem so promptly purchased another one (and more powerful) but the problem remains. When flicking the PSU switch on, the motherboard LED lights up, the fans rotate for a split second and stop, but pressing the case power-button does absolutely nothing. No fans, no noise, no nothing!

Does anyone have any ideas?!!

John.

[saphalline]

Hmmm... try resetting the CMOS for starters.

For a more in-depth diagnosis, you can try Sylvander's flow-charts (check the stickies). And of course we'll need more info on your hardware.

[JRP1414]

Ok thanks for your help, I'll have a go at that.

I'll post some more details, can't exactly remember what I put in there as it was some time ago now!

Do you think it could be a capacitor problem as described in some of Pete's info?

[Sylvander]

Sylvander’s Diagnostic Flowcharts
Download a copy of my diagnostic flowcharts from here
www.erniek.eclipse.co.uk/downloads/sylvanderdiags.zip
and print them to leaf through.
Begin on the STARTUP chart.
-----------------------------------------------
NO POST, NO BEEP, NO VIDEO
www.pcguide.com/vb/showthread.php?t=39685
-----------------------------------------------
I think the charts will help clarify things, but I doubt if they'll supply an easy solution to this.
I think the key to understanding the cause may be that click.
I've heard that before on my PC, but cannot clearly remember the circumstances.
It may have been when I once connected a USB plug into the socket the wrong way round. As soon as it was connected there was a click and the PC powered off.
So my guess is that the click is the sound of the switch that shuts down the PSU. Possibly because of a short or incorrect connection.

[JRP1414]

I'm still struggling with this and have come to the conclusion that the CPU is fried or something! I've checked every last track and pin on the mobo and there's no signs of poor connection or overheating etc. I've removed everything and reseated it but still no luck! Re-set the BIOS and dusted until you could your dinner off the damn thing!

Here's a rough idea of what's in the case (from what I can remember!):

Asus A7N8X Deluxe Motherboard
AMD Athlon XP2600+ CPU
256MB PC3200 DDR RAM
Hercules 3D Prophet 128MB Graphics card
A basic 20GB Hard Drive
CD/RW, floppy, etc.

Has anyone got any thoughts on the above spec? I'm thinking about buying the same components, one at a time, starting with the CPU, to see if I hit pot luck with replacing the faulty one.

Just another quick question whilst I'm here .... If you're having problems with high temperatures, what would leaving the side of the casing off do? Would it be detrimental, by reducing air pressure/flow, etc or could it help by increasing circulation of cooler air? Just something I've been considering!!

John.

[Sylvander]

"I'm thinking about buying the same components, one at a time, starting with the CPU, to see if I hit pot luck with replacing the faulty one."
Any chance to beg, borrow, or steal parts you can use to temporarily swap in?

"what would leaving the side of the casing off do?"
Allow hot air to easily escape by convection and be replaced by cooler room air.

"Would it be detrimental"
Most unlikely. Only if the fans were so efficient at producing a rapid through flow-rate that it was much more efficient than natural and unrestricted convection currents, and taking the panels off ruined that efficient setup.
Very often, adding fans is just an attempt to reduce [not eliminate] the worst effects of enclosing the heat producers.

[Fruss Tray Ted]

Do a barebones boot before condemning the CPU.

At the same time, reseat all physical connections a couple times each to make sure there's no corrosion preventing good contact with pins to sockets. This includes RAM, ide cables and such, also all fan header connections.

Also test the RAM with Memtest, but I think you will find it's hardware related.

When the fans don't start right away, there is no signal to the 'power good' sensor so you'll get these symptoms. So it could be one of those as well.