Sounds like a truck backing up.

I bought a 32 Meg SIMM, double sided, speed unknown, 80(? - tried to count them last night, eyes are getting old) pins, to complement what Darrell gave me. The problem occurred when I added it to the motherboard to bring the P166 system up to 64 Meg. Reversed them in the slots - still beeps. Pulled out the new simm and it rebooted successfully. Leads me to believe that there's something wrong with this simm.

One thing I didn't do is boot with the original simm in the other slot. I'll try that tonight; maybe the slot is bad for some reason.