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