computer restarts after a certain period of time

hi there. in our school i am the Ict tech and recently the dell optiplex 745 sometimes just restarts for itself....any idea what could be causing this and how to solve the problem? it does not happen all the time
brian ramdhaniCT Technician Asked:
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Dave BaldwinFixer of ProblemsCommented:
I would turn it off, clean out the dust bunnies inside, and reseat all connectors and cards.  Also, make sure it's got an adequate air path for cooling.  You could have something failing gradually so you might want to back up anything important on the machine.
Check CPU fans and working and that no over-heating issues.
how often is sometimes? several times a day? Once every 2 or 3 days? Has anything new been installed, software/hardware? Did it just start? How long have you had the pc?
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That symptom is often caused by a failing power supply. Have the PSU tested or try replacing it.
All the reasons above could be the problem or part of the problem.
The most common reasons:
1. Overheating (as advised, you need to clean/remove the dust).
2. Bad fans.
3. Bad memory.
4. Bad Power Supply.
5. Bad motherboard.
To troubleshoot I would suggest you take a look at the attached pdf. It will teach you how to use the Dell diagnostics software and how to interpret and use the diagnostic lights on this computer.
I hope it helps.
Bits ....


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Also... it might be helpful if you take a look at the event logs and see if something is being reported.
Bits ...
brian ramdhaniCT Technician Author Commented:
to answer ggefter...i understand it happens every few days....nothing new has been installed...the pc is around 3 years old and still has warranty with dell....this problem only recently started.....
you can monitor cpu and disk temperatures with speedfan :
it can be a bad PS, or mobo,  so check also for bulging or leaking capacitors.
thats the magic phrase "still under warranty", contact Dell and let it be their problem. Let their script monkey's tell you whats wrong and have them fix it while you still can. Regardless of if you find the resolution to the problem yourself, its still going to cost you money to fix it unless you submit it for warranty work. Let them replace every part in the machine untill it stops restarting at no cost to you
check also what is runnign with task management : applications, scripts..
I will totally agree with ggefter's comment above. Let Dell handle it, that's what the warranty is for. Only one more thing to add: Make a backup of your data. I would not trust them to do it.
Bits ...
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