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Computer starts for a few seconds, then dies

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February 16, 2011 8:25:02 AM

Hi,
Thanks in advance for any help with my problem!

So 2 days ago I after I'd been away I tried to switch on my computer and it seemed to be booting for about 3-5 seconds then die. Fans started, lights came on, think harddrives started. I had to go out for an hour or so, when I cam back, it booted up now problems.
Yesterday it booted up fine in the morning and left it on all day, couple of restarts and no problem.
This morning it's back to not booting properly. First time it started to boot for about 10 seconds, then second time i tried about 5, then down to 2 or 3 after that.

Anyone got any thoughts?

at the moment the situation is I've stripped the system down (still in case) to PSU, Mobo and CPU. When power is connected, lights are on on the mobo. When I try to boot, fans start up for a couple of seconds then it all dies. No beeps.

Is it possible/likely that the mobo/psu/cpu is fubar, given that it worked fine for a day after the problem first occurred?

Thanks again


specs:
Q6600, Abit FP-IN9, OCZ 600W SXS, 4 x 1GB OCZ RAM, GTX260 GPU.
Nothing new, internals haven't been touched in months.
February 16, 2011 10:37:56 AM

Automatic assumption to start is at the CPU overheating? then look for any swelling Capacitors and finally try a different power supply, you going to have to do a process of elimination on this one.

Sweet..
February 16, 2011 1:33:35 PM

Pilk said:
Automatic assumption to start is at the CPU overheating? then look for any swelling Capacitors and finally try a different power supply, you going to have to do a process of elimination on this one.

Sweet..


Cheers for the reply. I'm assuming that the CPU overheating would cause it to shut down to stop it destroying itself? I was wondering this, but the problem has only occurred from a cold start, being off for at least a night.
Yeah had a look for caps, couldn't see anything wrong!

My gut feeling is the PSU - I have lights on my mobo to show that it's receiving power from the PSU when the system is off - but I'm guessing lighting these doesn't necessarily mean that it will be able to boot the rest of it?
Also tried shorting the PSU power on with the ground on the mobo connector (briefly) and that worked fine... but I guess same goes for that?
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February 17, 2011 6:55:56 AM

Work systematically through our standard checklist and troubleshooting thread:
http://www.tomshardware.com/forum/261145-31-read-postin...
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

Breadboard - that will help isolate any kind of case problem you might have.
http://www.tomshardware.com/forum/262730-31-breadboardi...

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
http://www.youtube.com/watch?v=5FWXgQSokF4&feature=yout...

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
February 17, 2011 11:06:22 AM

Use JSC's response it is a break down of system of elimination. But yeah lighting and the rest don't count for much i recommend taking it in to you nearest computer repair place and get them to quickly bench it with one of there spare power supplies, not even the proper power supply testers i use in my industry work correctly as the item needs to be under-load to truly show any fault.

Sweet....
February 17, 2011 12:08:43 PM

Thanks a lot for the help,
I'll go through that list - I've also got my DMM now so can try testing the PSU in a bit more detail. If that fails then to a PC repair shop!
Thanks again
James
July 15, 2012 8:07:37 AM

This defect has happened to me and I have resolved the issue. I have found that on many forums the answer to the problem is never posted, so here goes.
A few days ago my 2008 Mac Pro would shut down when put to sleep. It then wouldn't start and only came on for a few seconds with the fan running, then click off. I spent an hour and a half on the Mac help line at a cost of £35.00, but they were unable to resolve the problem and they booked me in at the local Apple store. I asked the helpline if they thought it was the BIOS battery, but they said it wasn't.
In the Apple store, they concluded that it was the power supply, but I wasn't convinced as the fan ran for a few seconds before switching off. I asked them also if they thought it was the BIOS battery, but they said it wasn't. In the end, I decided to bring the computer back home. I opened it up and removed the BIOS battery and checked the voltage which was fine. I then refitted it and pressed the power button. Hey Presto! It worked fine! It is powering up, sleeping, restarting and shutting down just fine at this time.
When a computer starts it first looks at the BIOS for clocking and time. If there is a problem it can't go any further and switches off.
Apple wanted me to spend £165.00 on a new power supply which wouldn't have fixed the problem, so they would then have wanted to change the motherboard which wouldn't have been cost effective. I was going to buy a Mac mini instead, but am now able to continue with my Mac Pro for the time being at least.
I hope this helps.
August 23, 2012 5:26:10 PM

Rich Martin said:
This defect has happened to me and I have resolved the issue. I have found that on many forums the answer to the problem is never posted, so here goes.
A few days ago my 2008 Mac Pro would shut down when put to sleep. It then wouldn't start and only came on for a few seconds with the fan running, then click off. I spent an hour and a half on the Mac help line at a cost of £35.00, but they were unable to resolve the problem and they booked me in at the local Apple store. I asked the helpline if they thought it was the BIOS battery, but they said it wasn't.
In the Apple store, they concluded that it was the power supply, but I wasn't convinced as the fan ran for a few seconds before switching off. I asked them also if they thought it was the BIOS battery, but they said it wasn't. In the end, I decided to bring the computer back home. I opened it up and removed the BIOS battery and checked the voltage which was fine. I then refitted it and pressed the power button. Hey Presto! It worked fine! It is powering up, sleeping, restarting and shutting down just fine at this time.
When a computer starts it first looks at the BIOS for clocking and time. If there is a problem it can't go any further and switches off.
Apple wanted me to spend £165.00 on a new power supply which wouldn't have fixed the problem, so they would then have wanted to change the motherboard which wouldn't have been cost effective. I was going to buy a Mac mini instead, but am now able to continue with my Mac Pro for the time being at least.
I hope this helps.



Rich - Just wanted to say thanks for your submission to this thread. Had the same problem with a friend's computer, and found your post with a Google search. You definitely saved my friend some $$$ (I'm in the US) and, no doubt, saved me hours of troubleshooting. Many thanks from TEXAS, USA! Randy Crist
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August 23, 2012 6:29:11 PM

This topic has been closed by Mousemonkey
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