System randomly auto-reset and auto-off/-on

[tbytes]

Good day to everyone,

I've bought some parts of my system (processor, motherboard, memory, graphics card) this January 2007. Here are the specs:

Intel Core 2 Duo E6600 2.4GHz
Asus P5B-Deluxe
2GB DDR2 paired Corsair XMS2 series (placed in interleaved mode)
Nvidia 7600GT 256MB 128-bit
4 Storage devices:
-1 Seagate 80GB SATA
-1 Seagate 250GB SATA
-1 Seagate 40GB PATA (master)
-1 Sony DVD-Writer (slave)
535 Watts Enermax EG565P-VE 24P
Samsung 19" 940BW (connected using DVI)
Leadtek Winfast TV2000 Tuner (PCI)
Standard A4Tech PS2Keyboard
Brandless USB optical mouse
Windows XP Service Pack 2

The problem started two days:
-the system randomly resets itself at random stages of boot/use: before POST could begin (before the first beep when the basic info on the graphics card is displayed); during POST; in the BIOS setup; after POST; during OS startup; OS running, idle or in use.
-at random, either after an auto-reset or manual power-on, the system will immediately (before the basic info on the graphics card is displayed) auto-off for 3 seconds then auto-on.
-at random, after an auto-reset, the screen will just be blank and the power button won't work, even after pressing it for more than 4 seconds.
-at random, though seldom but only after an auto-reset, BIOS would report that I have misconfigured my overclock settings (sorry, I can't recall the exact statement) even though i have never overclocked my system or tampered w/ the timings and voltage settings.

What I have tried:
-removed all of the connected peripherals, except for the DVI, keyboard, & mouse.
-removed the Leadtek Winfast TV2000 Tuner.
-booted w/o peripherals (including the display) and w/ data/power cable for storages devices unplugged.
-loaded the default BIOS settings.
-performed a hardware reset (removed battery, shorted the reset PIN, waited 20 secs, unshorted the reset PIN, installed the battery).

Some notes:
-the motherboard never beeped any error messages.
-never overclocked my system or tampered w/ the timing and voltage settings.
-CPU temp is at 51C~54C (in BIOS) and 46C~48C (in Windows; idle) (i dont know the ambient temp, but I leave in the tropics).
-tried swaping the memory; used the memory slots 3 & 4; used only one of the memory modules (tried very memory slots, and the other memory module).
-My PC doesn't have any internet connection.
-Although I suspect its the motherboard that's the problem, I'm not ruling out the other components: memory, graphics card.

Since its my PC at home and its my shift at work, I'll need all the solutions you can throw so I can do as many test as possible when I get back at home.

Regards

[Raze664]

Fans look like they cannot take the whole heat. Can you get more fans installed on the case. My computer runs at about 30 idle and about 37 just after gaming.

[tbytes]

Thanks for your reply.

The temp might be high, but weeks ago before this problem (while I was more into playing games than just watching DVDs), the temp could max at 65C for hours at a time w/o problem, even during the day.

Also, just tried running my system w/ the motherboard out of its casing, w/ only the DVI & keyboard connected to it and w/ only one memory module. The system still suffered the same random resets and power-off/-on. Even w/ a different HSF (w/c is a little bigger and noisier but has much more airflow), it didn't make any difference.

After about 6~7hrs, I might be able to get hold of a spare PSU, memory, motherboard, & CPU for testing.

Thanks again for the reply.

Everybody please feel free to pitch in your ideas.

Regards