U.Mac, thanks, I did read that. I must have the later type of system board since I'm using the INET36WW bios and my FSB is running at the full 100MHz. My P3 is reporting the correct speed of 500MHz. My 600E is a 2645 8AU. I wonder how people figured out the existing Bios CMOS mods to disable the onb...

... you might be having a hardware problem....maybe the ram slot is either dying or working itself loose from the board... I agree that it may be hardware, but it's NOT a physical socket / connector issue. Because I can also get the full 512MB of memory recognized by running the memory test program...

I am using two 256MB memory sticks in this 600E, Crucial/Micron 100MHz, CL2. They are both the same part#, MT16LSDF3264HG-10EE4. Sometimes it does not see the second RAM on powerup, sometimes it does. In either case my OS runs fine (Ubuntu Feisty), have never had any problems or memory errors. Here ...