I recently acquired a 512MB DIMM of PC-100 RAM and put it in a Yikes! G4. I got it to boot up once, then afterwards it would turn on but not boot. Before: 256+128+128+128 After: 256+512+128+128 (where the first (256) is the innermost slot, furthest from the top edge of the case door) In the "After" configuration, the OS only reported half (256) of that DIMM. I tried it in other slots, with and without some modules, but it would only turn on, not boot. The DIMM has Samsung chips, k4s560832d-tc75. Google seems to think of this as registered RAM, yet this DIMM (I'm told) was running fine in an iMac 500MHz for several months. Am I out of luck?