MDD boots and then goes to sleep immediately

Question

have a dual gig MDD and suddenly the thing just started going to sleep or powering down right after booting up.
i've taken everything out and unplugged eveything to bring it back to it's intial state; i've zapped pram; i've pulled the battery; nothing seems to help.
with the hardware cd as the boot, i get the following
Invalid memory access at %SRR0: 00034870 %SRR1: 00003030
USB Setup Error: 40140000 400001
bad Bus info CRC-16
Apple PowerMac3,6 4.4.8f2 BootROM built on 09/30/02 at 10:24:31
which made me think it might be one of the RAM sticks. so i've puleld them, tried with just one and still nothing, swapped sticks, no go. with the cd in, when it goes to sleep, upon waking i get:
Decrementer exception at %SRR0: 056106dc %SRR1: 00003030
at first i thought it might be the boor drive but since booting from the CD still causes the problem, my guess is the MoBo.
if anyone can help me out, maybe something i've missed so i dont have to spend $500 on a new MoBo, i would be very grateful

Answer 1

An overheating proc can definitely make the thing go to sleep. But I don't know what would make the fan power stop working. I believe that's controlled by the PMU, but you've reset that.
I've seen some pretty strange PMU-related behavior, so nothing would really surprise me. Just today, I found that my firewire ports weren't working - they'd power peripherals, but I couldn't get either of my FW drives to show on the desktop. I booted to two different internal drives and had the same problem. I reset the PRAM, NVRAM, and the PMU and no improvement. Finally, I unplugged the PRAM battery, hit the PMU reset button, and let it sit an hour before plugging it all in again and viola - firewire worked!
It might seem redundant, but if I were in your shoes, I'd unplug that PRAM battery again, hit the reset button, leave it out for a couple of hours, and then plug it all in again to be absolutely sure. Also, be sure never to press the PMU button twice between starts.