PC starts then stops automatically

Hi jephree, thanks for the response. I've managed to fix the problem (fingers crossed), the open case was a red herring and for whatever reason it seemed more likely to run without the side on.

I thought the motherboard was shorting somewhere so I cleaned it up as best I could especially around the case header pins. As that didn't seem to work I was prepared to take the whole thing apart and give it a proper clean. However I read somewhere else that it could be shorting on the USB header pins, so I removed all the devices connected to all the USB, and firewire pins gave them a quick clean and it seems to have fixed the problem.

I've now re-attached all the USB devices and it's running as it was so all being well that will be it and if anyone else has similar problems I hope this helps.

Well after a few days of me putting the PC back together, and finally putting it back in it's hole (my desk) it was working as it should but today it's started doing the same thing again. I was in the middle of something when I heard the distinct noise if the HDD, not the usual clicking but like a 'burp' then a message saing I should save before shutting down.

So saved my work and powered down. When I hit the power button it starts for about 4 secs then stops, and it tries to power itself up without me touching it. When I switch it off at the mains then switch the mains back on, it will power itself on again without me touching it.

I've disconectted all the USB headers again and the first time I fired it up it started itself and swithced off. A quick blow of the mobo and it's back to normal so I think I'm on the right track with the system shorting somewhere. I may have to take it apart and give it a proper clean after all.

Any suggestions would be great, especially if it saved me from taking it apart. If not I'll post my findings after the overhaul

Originally Posted by jephree

The auto start might be a BIOS setting to auto start after power loss. If this is set then it would try to turn itself on after any indication of a power loss.

The 3 or 4 second issue reflects the fact that holding the power on button for 3 or 4 seconds is designed to shut off the computer. If the BIOS is reading this as a power failure then the BIOS would try to turn it back on.

When you say you put it into it's hole it again raises heat issues.

Overall there is a growing suspicion in my mind of the PSU.

You can get a PSU tester at most any computer store such as:

LCD Power Supply Tester : PSU Tester : Maplin

Thanks again jephree, I'll look into the BIOS. I don't quite understand your explanation about the 3 or 4 second thing. Can you explain again please. I'll try and expain what happens so maybe you can relate it to that. The PC is powered by a UPS which I use as a master switch. So when I want to use the PC I switch on the UPS, sometimes the PC will power itself on without me touching the power button and sometimes I will need to press the power button to switch the PC on. Eitherway the PC powers up the fans will spin then after 4 secs everthing stops (LEDs fans etc, like power has been cut) then without touching anything the PC will power up again where the same thing happens again. Sometimes after 3 restart reboots, on the third attempt it loads into windows (after which it will turn itself off, power failure off), other times it stops and doesn't do a thing, just dead.

When I say put it back in the hole I just mean back into the desk, it's an open desk no door or anything like that. Recently when I've had to do all this stuff I need to pull the case forward onto the floor, whereas normally it just sits in a space in the desk about 2 inches off the floor, a very standard desk.

The PSU tester will be cheaper than getting a new PSU so if I'm still going roudn in circles I may have to resort to that.

I have tried removing the UPS from the equation, and no change, however I think you're right with the power button. I've disconnected the power botton switch from the board and start it up by shorting the pins with a screwdriver and so far it seems to be behaving as normal. So I think that could be it, I've since swapped the power SW and reset SW to power it up that way and so far so good.

All being well I will post a final report after a week and we can put this to bed.