Help: If I turn off my computer, I can't turn it back on.

makutaku · Post by **makutaku** » Wed Nov 26, 2008 11:17 pm

My computer is on 24/7. Sometimes, when I I had to power it off, I noticed it failed to turn back on. However, I just had to push the power button again and it worked fine.

But it got worse ... way worse. Now, if I turn it off, I have to wait more than an hour - with the power cable disconnected - to be able to successfully turn it on.
I'm afraid if I turn it off again, it will be permanently.

At first I thought it could be heat, but CPU and Video card temperature seems to be normal. Also, if I don't disconnect the power cable, it doesn't matter how long I wait.

I suspect either the motherboard or the power supply is failing. If I borrow a PSU from my HTPC, my wife will complain.

So I wonder if someone in this forum could please give me some tips on how to efficiently investigate this issue.

Some info:
* When it fails to turn on, there's absolute no beep, no led, nothing.
* When it succeeds, it always boots correctly.
* There's no overclocking going on.
* CPU is DualCore AMD Athlon 64 X2, 3800+
* Motherboard is Abit KN8 SLI

Happy Thanksgiving!

-makutaku

Post by **NeilBlanchard** » Thu Nov 27, 2008 3:59 am

Hello,

I have had this happen as well. I had to reset the BIOS and wait 30-45 minutes -- the solution was to replace the motherboard. Something on the motherboard (possibly capacitors in the power supply section?) have failed or are starting to fail, and the best solution is replace the motherboard, unfortunately.

I hope you have a happy Thanksgiving.

hybrid2d4x4 · Post by **hybrid2d4x4** » Thu Nov 27, 2008 4:42 pm

It sounds like it's a bad mobo as Neil said. The only way to be certain would be to try a known-working PSU, but if you really don't want to do that, I have another idea to help eliminate the possibility of the PSU being the culprit:

When you have the situation occur where you can't power on the system after turning it off, disconnect the 20/24 pin ATX connector from the motherboard and force-start the PSU using a metal paperclip or something between the green pin near the said connector's clip and one of the adjacent black ground pins (pins 13+14 on http://info.ee.surrey.ac.uk/Workshop/ad ... nnPSU.html). If the PSU powers on (it's fan starts spinning) then the PSU is deemed ok, and you can be more confident that it's the mobo. If the PSU doesn't start, then the caps in the PSU are the problem. You may have to google "test atx power supply" or something like that if my instructions aren't too clear.

makutaku · Post by **makutaku** » Sat Nov 29, 2008 2:49 pm

Thank you hybrid2d4x4 and Neil!

You guys were right: it's the motherboard!

Using a metal paperclip, I noticed that the PSU started right away. Then I reconnected to the motherboard but it couldn't start right away, just later.

Thanks a lot for the tip!

-Makutaku