on 3/13/2012 11:07 AM Ross Walker spake the following: > On Mar 13, 2012, at 12:50 PM, Alan McKay<alan.mckay at gmail.com> wrote: > >> Back about 3 months ago I took this system down and removed all the RAM, >> and stuck individual chips into it and booted it, testing each chip on its >> own. At that time every single one of them worked! But I'm about to try >> this again to see what happens. Back then I also ran memtest86 for some >> time and it seemed OK too. > > It could be a bad physical RAM slot on the motherboard. Try filling the slots one at a time (or two if paired) until you hit the problem slot. > > -Ross It could also be a power supply problem... Add memory load, and a bit of heat, and voltage drops a bit...