Not 100% sure,but i think its to do with the speed of your dimms,ie when you take your cpu past 366mhz it runs at 100mhz if your dimms are 66mhz,it will cause your system to hang or not boot at all.
hope this was some help.
I think the message means that the memory controller could not find the serial EEPROM memory that all PC100 compliant memory modules have. The EEPROM is a small 8 pin memory chip that tells the mempory controller the size, speed, and other characteristics of the memory module so it knows how to set up the timing for it.
I got a similar message at boot up a few weeks ago when I put a cheap non-PC100 compliant memory module in my system. It ran OK, but the BIOS had to assume a bunch of timing for 100MHz operation.
If your package says 100MHz, that's not the same thing as PC100 memory! PC100 memory is actually 125Mhz memory (8nS or faster). If your memory chips have a -10 on the end of them -- and I'm betting they do -- then you don't have PC100 memory.
100MHz memory might run OK with your FSB set to 100MHz. If your system gets flaky, backing off the FSB frequency a bit should stabilize it.