Thanks for Memtest86+; I use it several times a year to test motherboards, and I would be lost without it.

On the last two motherboards I tested it on, both from SuperMicro, Memtest86+ always failed in SMP mode, but would pass the motherboard and memory if run on only one CPU. As I recall, Memtest86+ always failed in relatively the same place -- block moves in the higher memory regions. I am using both these boards, with the memory on which the test failed, with of course all CPUs active. So, it could be either a Memtest86+ problem or a SuperMicro problem.