Unintended power off in XP safe mode

exocett

Distinguished
Jun 16, 2009
2
0
18,510
Recenly I found whenever my windows xp sp3 booted into safe mode, my system just powered off all by itself after about 2 min. without any warning (not BSOD).
Before it shutdown, everything looks ok. Desktop icons all show up and everything seems operational. Explore and softwares run fine, and I can even do regular shutdown or restart, but I have only about 2 minutes.
Except this safe mode insanity, my system is quite stable in normal mode. I can have it works whole day (probably half day or at lest 12 hrs continously). In normal mode, I ran prime95 and 3dmark 06, they all turned out ok. I have also setup another xp sp2 to other HD from my initial xp installation cd just for the test.
I did'nt install any drivers or do any xp updates. But again I got this safe mode power off, still only in safe mode. Does anyone have any clue about this abnormality? (my first quick guess it is very likely to do with hardwares, but how, cause it is quite normal in regular mode.)
My system spec. in brief:
CPU: Athlon 64 x2 5000 (temp around 40-45 degree c measured by Everest, no OC)
mobo: msi k9n2 plat.
memory: adata 2g*2 in dual channel (voltage 1.9, no OC)
display: dual 9600gt (sli and physx on (driver-178.24 from msi, temp 50 degree c)
psu: corsair 620HX
attached with: 4 internal HD, 3 optical (2 ide 1 sata), 4 external HD (usb).
pci: one gigabyte usb card, one leadtek tv/radio card.
 

exocett

Distinguished
Jun 16, 2009
2
0
18,510
I have already done myself a couple of tests.
I took out one video card and used a single graphic card; no luck.
I then disconnected all the external usb drive (4 of them, and single graphics) and internet connection (with cable took off), still got automatic shutdown in safe mode.
Again, no apparent problem in normal mode.
Am I missing anything? Desparately need help. Please, anyone?