Turns on for 5 seconds, turns off.

I just replaced the heatsink on the processor on my abit VA-10. All
other components are the same.

What happened is, I plugged the power cable back in to the PSU, and as
soon as the plug went in, the machine turned on (without me turning it
on), for 5 seconds, and then turned off.

I then tried powering it on, with the button, and it does the same
thing, on for 5 seconds, off. It does not post. No beep codes. The
heatsink's fan is spinning fine. This really can't be an overheating
problem since it's only 5 seconds we're talking here.

 

If the heatsink is not (or only slightly) touching the cpu then it
would take 5 to 10 seconds for it to overheat. If you repeat the
action then it never cools off and it overheats immediately.

Forrest

Motherboard Help By HAL web site:
http://home.comcast.net/~mobo.help/

 

Well, the heatsink is clamped on (socket A). I mean, how can it not be
touching?

And what about the symptom of it turing on when it got plugged in?

 

Also, if it was overheating it would give the overheating beep.

 

Believe me - it might not be touching. It's very hard to tell even if the
heatsink 'looks' as if it is performing properly. Removing the sticky
heatsink compound pad and using a little thermal grease is usually a better
solution than the pad provided. When the Athlon XP first appeared, I had a
CPU burn out in about 8 seconds because the heatsink wasn't touching the CPU
properly because of a faulty (slack) spring clip. To all intents and
purposes a visual inspection beforehand left me confident that all was well.
It wasn't. Luckily my supplier agreed with my diagnosis and replaced both
the CPU and heatsink.

The other main cause of the symptom you describe is usually that the
heatsink fan has been attached to the wrong power header on the board and
because of a CPU protection facility built in to the board, power is
switched off as soon as non-rotation of the fan is detected. Of course the
tachometer wire/connection (third wire on fan) could be broken or otherwise
not making contact.

Quite a lot of boards 'kick' the CPU fan briefly when mains power is applied
to the PSU. Check your front panel connections are correct on the board.
Make sure your case doesn't have a stuck reset switch, although this usually
causes the PC to power on and stay on but not boot.

Ensure that nothing else is causing the fault - remove everything except the
graphics card, CPU (and cooler) and memory, and keyboard. If you can get it
to boot in barebones mode, then reconnect other components starting with the
hard disk one-by-one to identify the culprit.

 

Make sure the cpu fan is plugged into the fan header marked cpu.

 

right ... and the fan is doing more than 1500rpm, otherwise "cpu
protection" could work if enabled.

 

Yes indeed. Your confident the pc speaker is working?

I don't know first hand but I have heard others mount the heatsink
mounted 180 degrees rotated and then partial contact occurs.

My functional system seems to like to turn on when I plug it in, on
occasion, too even though I have set it to not-do-that in the bios.
Don't know why. Not really a concern since its on a backup power
supply. Don't know what VA10 bios defaults to...

Forrest

Motherboard Help By HAL web site:
http://home.comcast.net/~mobo.help/