Computer is rebooting for no reason

[Svnla]

Client has generic pc with pent 4 3.0Ghz, 512MB RAM, Intel motherboard. The computer is reboot when it shows the windows XP screen or about 15 seconds after that. No beep, nothing, just reboot like someone hits the reboot button. Sometimes it will stop at the black choice screen of safe mode, safe mode with network support, and so on. I tried all the choices and still the same thing, reboot and we are back to square one.

No hardware or software add on at all. The computer just get worse and worse <used to reboot once a while, then a week, then a day, now you can't even log in and use it>.

The client has about 3000 computers and they have a lot of thermal overheating and reboot <as mentioned above>. Any suggestions or ideas? What are the main cause(s). TIA.

 

[Boonesmi]

first thing i check when a pc start random rebooting is the memory (memtest86+)

 

[kitkat22]

My guess would point squarely at the PSU. Take a look at the brand and specs. Maybe even overheating.

 

[VirtualLarry]

Bad caps on the mobo can do this. (If it's not the PSU.)

Check to make sure that the CPU fan is turning, and it's not because of the mobo's thermal-shutdown/reboot feature due to overheating.

 

[Slugbait]

Saw these exact same symptoms on two different machines. Both had dead video card fans.

 

[Zepper]

I look at PSU and memory first on rebooting.

.bh

 

[GuitarDaddy]

Look in bios for a setting to auto restart on fatal error, and disable it. Then see if it stops on a bsod and gives error codes