Okay so running Sandra, I got:
So, it looks like we've found the biggest bottleneck. That's the right chipset (i'm pretty sure), but the memory speed is a bit high on the reference system (mine is 3200), so I tried again with something that was hands-down worse.
So, something is definitely fucked up here. Running the performance checklist results in this:
Right in the summary: "Large memory modules should be ECC/Parity." I have no idea what the hell this means, but I'm going to go spelunking in the BIOS to see if I can't find out. Ideas?