Install went without a hitch. 4 single sided dimm's, 2 gigs of dual channel yumminess. SPD set 'em all to 400. Glad about that. Thought my BIOS or their default would be some 'safe' value.
With 4 slots used, and admittedly a hint of power issues I've had with the 6800.. I upped the voltage to AGP and CPU a notch and cranked out a few more MHz to offset the hint of performance loss.
Alrighty. Time to boot up oblivion and test a bit.