help .. pc restarts / shutsdown ! no clue of reason

[ide]

my PC keeps on restartng/shutting down on irregular intervals without any apparent reason,

the intervals at which the computer restarts or just shuts down are very random sometimes it restarts just when windows starts to boot and sometimes it restarts after running for many hours without any problem

sometimes I also hear a twisting and turning sound before the computer restarts ,, it seems that the sound
comes form the hard disk

sometimes the PC just shuts down and sometimes it also
tries to restart it self

when it only shuts down i have to 1st turn off and than turn on the power from the mains as without this pressing the power or reset button on the CPU does not have any effect

I have reinstalled windows many times but the problem persists , so this is most likely a hardware problem , however I am unable to pin point the device which might be causing the problem

i got this PC about 3 months back and this problem started appearing only about 15 days ago

the specs are

Pentium 4 3.06 processor
Kingston 1 gb ddr2 ram
Seagate 80 gb hd
Intel d102 ddc mother board

any help is appreciated

thanks:idea:

[Chaky]

Your problem is with HD power cable. Poor contacts make unrecoverable error with windows and they shut down (with or without BSOD). You can disable the "automatic shutdown while booting" feature, but that would be useful only with /SOS boot comand ("msconfig" in the "run" menu item).

I suggest that (if this is retail PC) you use the waranty. Some retail PC's has waranty sticker on the casing, so if you open it up, you will tear the sticker and void your waranty.

If this is a custom-built PC, try changing the power and ide/sata cables on your HD.

[ide]

/\
thanks .. to narrow down the problem i unplugged the hard disk cable and kept the pc running .... the problme still appeared .. computer hung for a while and than got shutdown ...so we can say that the problme isn't with the hd

what else can be the reason ?

thanks

[ide]

I have also noticed that .. when there is noise from the hd than the motherboard fan also seems to slow down and than after a few sec the computer stops ..

Now i hav given seperate power to the hard disk from another old P3 power supply , computer has restarted once after that ... but there was no noise from hard disk before the computer restarted .. only the hard disk has been given the new powersupply rest of the things are still on the p4 power supply

to me it looks like a issue of an unstable power supply

any comments are welcome

thanks

[Chaky]

I believe that you are on the right track.

Getting new PSU would be the cheapest remedy. You don't have to wait until something like CPU ($$$) dies because of it.