So I have just run through a battery of tests and am pretty sure that the outer slot (I'll call it slot 2) for my RAM is bad. I have run memtest multiple times. both sticks either order = failure stick a/slot 1 = ok stick b/slot 1 = ok stick a/slot 2 = failure stick b/slot 2 = failure AHT gave the same type of thing when I did the extended test. My mac is out of warranty so I have no coverage there although it was bought with an AMEX card. From what I understand they extend warranty by another year on top of the manufacturers warranty. Has anyone done this before with AMEX? Also, is there something else I can try that I might be missing? Thanks!