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Desktop PC keeps randomly turning off

Posted on 2011-09-12
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Last Modified: 2012-08-13
Dear Experts

I've been experiencing this frustrating problem with my desktop. It will randomly turn off, i.e. completely power down without any errors on screen.

Things i've done:

I've had a look at the event viewer and there isn't anything that stands out.
Opened the case to check all the fans are spinning when powered on.
Checked to make sure everything is well seated into the Mobo.
Re-applied themal paste to the processor in case it was overheating.
Swapped out my 450W PSU with a 500W PSU i had.

Not sure what else to try.

The problem began roughly when i upgraded my gfx card but i have since put my old card back in but i'm still getting the problem.

Any ideas?
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Question by:Bladey001
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11 Comments
 
LVL 17

Expert Comment

by:Shanmuga Sundaram
ID: 36522441
try using some hardware monitoring tools to view the CPU core temperatures, we can check  if it is overheating.
try restarting in safemode and see whether it turns off
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LVL 88

Accepted Solution

by:
rindi earned 1600 total points
ID: 36522521
How did you reapply thermal paste? Did you first make sure that both surfaces, that of the CPU and the heatsink were absolutely free of old thermal paste or whatever had been used? Did you apply just a very small drop of paste, and make sure the heatsink was attached firmly and correctly to the CPU?

Normally such types of shut-offs are very much due to overheating....

Another reason could be bad capacitors, so check the mainboard for any signs of leaking, bulging or cracking caps.
0
 
LVL 7

Expert Comment

by:karllangston
ID: 36522665
What OS is this? have you run any AV AntiMalware Scans? maybe you should try things like Malwarebyes / SuperantiSpyware if the Hardware side of things looks OK
0
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LVL 69

Expert Comment

by:Callandor
ID: 36522902
How old is this desktop?  If it's old, the motherboard may have some capacitors that have gone bad (www.badcaps.net).  Randomly turning off is generally a motherboard power problem or a cpu overheating problem, as mentioned by others.
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Author Comment

by:Bladey001
ID: 36523312
shasunder:

i will try that and see what i get

rindi:

i didn't scrap off the old paste, in fact there was hardly any left anyway. So i applied a pea sized amount into the middle and spread evenly over the processor. Yes i made sure it was firmly re-attached.

karl:

Running Windows XP SP3. I haven't ran Malwarebytes for a while, i'll give that a go

Callandor:

Its a custom built desktop, roughly 3 years old.
0
 
LVL 88

Assisted Solution

by:rindi
rindi earned 1600 total points
ID: 36523417
You should really get rid of all old paste. Often it isn't paste, but a kind of plastic that melts at first use then gets hard again. That has to be totally removed.
0
 
LVL 92

Expert Comment

by:nobus
ID: 36527802
any minidumps in  windows\minidumps?  if yes, post latest
also, calculate the power you need for both cards  :  http://www.antec.outervision.com/
for the temperatures, install speedfan to monitor them  : http://www.almico.com/speedfan.php      

you can also test ram and disk, so download ubcd, and run memtest86+ for 2 passes, and the long disk diag, to be sure about the basics : http://www.ultimatebootcd.com/      
0
 
LVL 10

Expert Comment

by:Mohammed Rahman
ID: 36532828
Turn ON the system and let it be ON for around 10 minutes. Place your finger on the CPU heatsink and feel how warm/hot it gets. Wait until the system shuts. As soon as it shuts, place the finger on the CPU heat sink again and notice if there is huge difference in temperature. It should be a little hot/warm more than your felt initially. Also, try touch the bridge (nort and south) heatsink on the MOBO.
0
 
LVL 88

Expert Comment

by:rindi
ID: 36534379
That test wouldn't help much if the heat doesn't get from the CPU to the heatsink which is usually the case if the fan runs OK but the heatsink isn't tightly attached or the thermal paste not correctly applied (or rests of old thermal plastic obstructing the heatflow).
0
 
LVL 5

Expert Comment

by:Paul Smart
ID: 36546712
Sounds daft, but check for fluff in between the pins of the power button connector on the motherboard, I had a recent machine that had the same fault, and tuned out to be electrically conductive fluff.

This might not work for you but worth a check.

checking the motherboard for faults also good as mentioned above, also any shorts accuring due to a poorly seated motherboard can cause the same, so it's worth checking that the motherboard is not shorting against the case at any point (usually where they connect to the screws)
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Author Closing Comment

by:Bladey001
ID: 36561963
Did as you suggested. Removed all the old paste, removed any dust, reapplied and so far no sign of the problem.
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