Updated to BIOS v1.05.
One RAM slot doesn't seem to work - sticks tested individually all work but 6 DIMMs populated show 80GB instead of 96GB. DIMM4 seems to be the culprit.
Tried reseating the RAM several times as well as the CPU to no avail.
EDIT: Definitely seems to be a faulty motherboard - tried a completely different RAM kit from my other system and DIMM4 simply won't see the RAM in that slot.