massive crash!

[Petruchio]

I am stumped. I have not found any documentation that explains my symptoms.  I built this box about 2 months ago and now I have 2 problems I think are related.

Box specs:
425 watt ATX power supply
BioStar M7NCD  Motherboard
AMD Athlon XP 3200+ (Barton core, 400 FSb)  CPU
All copper CPU heat sink - Ultra brand
512MB PC3200 DDR 400MHz RAM -  Ultra brand (with added heat sinks)
Hitachi 90GB EIDE HD
XFX GeForce FX 5200  256MB DDR 8X AGP  video card
Win XP Pro OS

Problem 1 I can live with if I have to. In the BIOS I have 4 possible settings for the bus speed  100 / 133 / 166 / 200. If I set the bus speed to 200, Windows fails to boot. The BSOD display says the failure was due to a memory error. If I back it down to 166 bus speed it seems to work. (at least for a time)

Problem 2 is the killer. The box crashes big time. When it crashes there is no warning in advance. It just whacks out... No Display... No way to re-boot... 3 finger salute is no effect... Power on button does nothing... The only thing the box does is keep sounding a 2 tone alarm from the internal speaker.  (beeeeeeeebooooooobeeeeeeeebooooooobeeee eeeebooooooo) The sound kinda reminds me of a police car in England. (I digress)  The system logs show nothing. It crashes so fast there is no time for it to enter anything in the logs.

The only way to recover is to unplug the sucker for about 15 seconds then reboot. CPU and Case temps are fine when this happens. I am wondering if the RAM is going fubar. Any suggestions short of a 10lb sledge hammer are welcomed.

[Raptor]

I suggest you donot attempt to overclock your System Bus to 200MHz again. This may damage your CPU permanently.

Are you positive you are getting stable temperature readings? And what do you define as 'fine case and CPU temperatures'?

[Petruchio]

I suggest you donot attempt to overclock your System Bus to 200MHz again. This may damage your CPU permanently.

Overclock? The Motherboard, CPU, and RAM were all designed to run together at 400. That translates to a setting of 200 in the BIOS. There is no jumper block for clock settings on this board.
http://www.biostar.com.tw/products/mainboard/board.php3?name=M7NCD is the link to the board specs. http://www.amd.com/us-en/Processors/ProductInformation/0,,30_118_3734,00.html is the link to the CPU specs.

BTW, minor point, on the AMD web site, the recomended motherboard for this CPU is the one I am using . . . Which brings me back to wondering how running at the rated speed is overclocking.

Are you positive you are getting stable temperature readings? And what do you define as 'fine case and CPU temperatures'?  

Well, not rock stable. Is a CPU temp. of 32C to 35C close enough to stable?

One tech I talked to said that a borderline power supply could cause the crash symptoms I described above. I replaced the PS with an Antec model True430 supply today. . . still crashes.

[Raptor]

Windows XP refuses to boot when I set my System bus to 200MHz, however, I have an XP Athlon.

What kind of power supply did AMD Tech-support recommend? The one you installed? I suggest you mail them again to see what kind of power supply they would install.