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Computer power shut down...

krusebr asked
Medium Priority
Last Modified: 2008-02-01
I have a system that ran great for a year but then for an unknown reason keeps shutting off without reason.  It powers off completely.  The only way I can get it restarted is to unplug the power supply and turn the power supply switch to off.  Then replug the AC back into the power supply and turn the ps pwr switch back on ... then start the computer again.  It is almost like the power supply is resetting for some reason.  I have replaced the power supply (500 watt) with another brand new power supply 550w.  The system runs fine and logs show nothing happening except just a hard power off.  I do have it plugged into an APC UPS.  Any suggestions of what to look for????

Tyan S2469 Motherboard - dual processor -
Watch Question

Hi krusebr,

Maybe a virus? A motherboard malfunction?
Sometime there's a circuit shortcut somewhere, and the motherboard shuts off the computer to avoid bigger problems.
My suggestion is you update your antivirus to find something. If you can't find, take it to anyone to check if there's anything wrong with your pc hardware.

Top Expert 2006

Check for overheating. If you don't have a monitoring program for your system, try SiSoftware Sandra: http://www.majorgeeks.com/SiSoftware_Sandra_Lite_d4664.html
Check your cpu temps and mainboard temps. Overheating cpu or mainboard can shut down the system.
Check your board for bulging, capping, or discharging capacitors..this would indicate a bad board.
Try removing the cpu and apply a thin layer of thermal silver and reseat with heatsink/fan firmly attached. Check that all of your fans are running as well.
Also test your ram: www.memtest86.com


Would this cause the power supply to reset though???
The only way I can get the system to restart is to physically unplug the power supply and plug it back in again.  Then turn the system on.  
It will not start again without doing the above process.
Top Expert 2006

My first thought regarding your problem would have pointed to the power supply. Since you replaced it, the psu can most likely be ruled out. It can also point to irregular voltages and surges from your power source (outlet), which can actually blow out the psu, so if that's the problem, a second psu could have been damaged, as well. Trying the system plugged into another circuit or with a UPS may show whether this is the problem. You can also have an electrician check for problems.

If it's capacitors or a bad board, unplugging the psu and allowing all power to drain from the board, then plugging it back in could allow it to restart. The same with overheating, by removing the voltages by unplugging the psu. It would be interesting to see if instead of unplugging the psu, let the system rest a few minutes to see if you can restart.

The best thing you can do is try to loacate the source of the problem. If you start with the most basic, by monitoring the temperatures and examing the motherboard, you don't have to start throwing money at the problem yet.

Another overheating issue can occur with the hard drives. When the system shuts off (while unplugged), check the hard drive(s) to see if the feel very hot. You can also do hard drive diagnostics: http://www.ultimatebootcd.com/ the Ultimate Boot CD contains diagnostics for major hard drive manufacturers, as well as the memtest diagnostic.

As far as faulty ram causing this behavior, it wouldn't be my first guess, but faulty ram can create intermittent problems, so it's always good to test it.

I has a system last week with the same symptoms . . I looked at the Capacitors and three were bulging, one was leaking.  ECS is replacing the board.
Top Expert 2006

Sorry, I just reread and saw you have it connected to a UPS. Even with a UPS, you can have problems with the voltages and noise from your ac source.
Question: How often is this problem occurring? If it happens reliably, you can try your individual components: CPU, RAM, Video, Hard Drive, PCI cards, on another system to rule them out. If they all check out, it leaves you with the motherboard, and psu and depending on your ac power source, electrical wiring or grounding problems.

Again, checking the temps and doing diagnostics is the easiest way to start.

This seems to me that is a power source related issue.
Try with another power supply and see if it does the same thing


As I stated in my opening, I have tried another "new" power supply and it is connected to a good UPS.  I will try some of the other suggestions above within the next couple of days and will get back to adding another comment to this issue.  Thanks to all who have responded already.


Ok, here is the latest.  This is what I have done so far.
Replaced the power supply with "new" and better.
Replaced the UPS battery backup with "new" and different power cord.
Monitored the cpu temps via the bios utility.  Does not get any warmer than 46 degrees celcius.
It seems that the server will run in bios mode without shutting down without problem.
It seems that after starting the server up (Novell 6.5) and leaving it on for a few minutes, it shuts power off.  Then as I stated above, I have to leave it set for a few minutes and cycle the PS on/off switch or unplug the power to it in order for it to start again....only to see it happen again.
I am confused. It seems that it is still power related or temp related.  Can the cpu temp go up after starting Novell server?


I was wrong!  It does shut down also while just sitting at a dos prompt using a startup disk.


So, if the bios cpu temps are under 45 celcius constantly and the power supply, ups, and memory tested OK, and it does the abrupt "power off" setting at a dos prompt starting from floppy startup....then it must be that the motherboard has developed some sort of problem????  Any help would be appreciated again.  Thanks.
Top Expert 2006

>>So, if the bios cpu temps are under 45 celcius constantly and the power supply, ups, and memory tested OK, and it does the abrupt "power off" setting at a dos prompt starting from floppy startup....then it must be that the motherboard has developed some sort of problem????  

Most likely, yes. But not definitively.

---To rule out the cpu..try it in another system, also, if you haven't already, reseat and apply thin thermal paste, make sure the heatsink has good contact.

---Rule out other devices...disconnect all other devices...hard drives, optical drives, pci cards..EVERYTHING except ram/cpu/fan/video/psu/floppy..try booting to floppy and see if there's a difference.

Removing the board from it's case to do this on a non-conductive surface like wood or cardboard is best. Hotwire it on by disconnecting the power-on switch from the mb and using a screwdriver to short the on/off pins on the board (or briefly jumper the pins and remove to start)

 IF not, disconnect floppy, connect cd drive, boot from cd and see if there's a difference. You'll have to do this several times if it seems to work, to assure you're not getting a false positive. If at this stage you are getting reboots, it would point to the motherboard (if, as stated and suggested, all other components were tested)

--If you were getting a good boot from the 'bare' system, adding components, a piece at a time will identify the problem. Remember to repeat several times before adding the next component, to assure you get a consistent result.
Top Expert 2006

BTW-Any bootable cd will do the trick, but a great resource is a live CD like Knoppix: http://www.knopper.net/knoppix/index-en.html
It's a self contained Linux-based OS.


Thanks for the additional suggestions....I will try them today and post results.

Upgrade the BIOS. It may have become corrupted.

something tells me the UPS is buggy. Try direct current and see if it shuts off.


as noted above, I have tried different ups


I think I have found the problem....
so far running for two full days.....
I took out the 2nd processor and it seems to be running ok.
The grease looks good on the processor I have out and fan runs properly.
Any good reason why this would be the problem????
PAQed with points refunded (500)

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