Oh, every dual channel setup was the same brand... I see.
Ok, some stupid questions first. Were the dual's in the right slots as per your MB's manual? (usually 1/2 2/4)
Did you enable dual channel in bios?
If they are passing memtests by themselves but not together, perhaps you have a bad slot? Can you experiment to see if you only have a problem with one slot?
(leaving work now, will get on later)
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