I've just put together the following system:
Asus P2B-D motherboard (rev 1.06 with 1013 BIOS)
Dual P3-600 Coppermines
256 (2x128) ECC PC100
Adaptec AHA-2940UW SCSI card
Dual Intel Pro/100 NICs
Matrox G200 AGP
Antec TruPower 430
and the problem is, when running XP, the system will suddenly enter suspend mode or something similar (windows doesn't say 'preparing to stand by'), even when the system is busy (ie i'm sitting there using it). By 'suspend' I mean the following. Monitor blanks, CPU fan stops, CD-ROM light stays on (odd huh), PSU fan stays on, power light blinks. This always happens after about the same time (10mins or so, haven't timed it). It's very hard to wake it up from this state. Pressing keys does nothing. It powers off via the front switch but goes straight back to the same state when you hit the power button again. It takes a CMOS clear (or sometimes fiddling with the SMI (suspend) switch header does it. The SMI header isn't connected to a switch. I tried leaving it shorted but then the boot wouldn't continue after detecting IDE devices.) or cold power-off and leave for several hours. XP is installed non-ACPI, couldn't get it to work with ACPI even though this is a rev1.06 board.
I've tried the following troubleshooting steps:
Disabled power management in BIOS and in XP (already had to disable ACPI or XP wouldn't install)
Changed PSU (also tried a Suntek 300W jobber)
Changed BIOS battery
Checked for overheating (nothing is hot to the touch, only warm)
Updated BIOS
Ran Windows Update
Any bright ideas would be very much appreciated