Help please: random reboot problem with new E6600 build

Here’s my original part list:

Asus P5B Deluxe
E6600
Tuniq Tower 120
G.Skill PC2 6400 2G
XFX 7600GS Fanless
Antec P180
Antec Neo HE550
Raptor 74G
Samsung DVD IDE
XP Pro OEM

I carefully built up the system and began experiencing random reboot problem. No particular software can be pinpointed, it was totally random and not under load.

Here’s the error message I got.

STOP:C000021a {Fatal System Error}
The windows subsystem system process terminated unexpectedly with a status of 0xC0000005 (0x******** 0x********)
The system has been shut down

I began my troubleshooting adventure.

Temp: The case is open in a cool room. Confirmed all 4 of my 120mm fans are running. CoreTemp says my idle is 27c and even with Orthos running it’s only 40c. So I feel my temp control is good.

RAM: tried moving to different slots, tried one stick at a time, ran MemTest for 8 hours with no error. Installed a different pair of Kingston RAM and still got random reboot. So I ruled out my G.Skill as the problem.

Video: put in a different new XFX 7600GT. Same problem.

BIOS: updated from 1004 to 1101. No help.

Virus/Malware: fresh OS with only diagnostic tools. No internet connection yet.

I RMA’d the MB and got a replacement P5B Deluxe – thinking maybe there was a bad circuit or bum capacitor. Also bought a new Corsair 520HX PSU. Installed them up and, you guessed it, same problem.

I switched HD to another Raptor 36G that I have and used a different XP Pro disc to install the system. Same problem.

Confirmed that Temps are still good: all 4 - 120mm fans are running.

CoreTemp: idle is 27c and with Orthos running it’s only 40c.
Speedfan: idle system 34c idle CPU 34c. With Orthos running, system 38c, CPU 50c.


The BIOS says my voltages are:
Vcore = 1.296v
3.3V = 3.312v
5V = 4.966v
12V = 12.091v

At idle Speedfan and Asus PC Probe II said my Vcore is only 1.14v and under load they register 1.29v.

The only suspect left for me is the CPU. Tell me it ain’t so.

I REALLY NEED SOME HELP TO TROUBLESHOOT NOW. THANKS FOR ANY SUGGESTIONS.