"The only AMD processors that can be run in DUAL mode are the 200 and 800 series Opteron processors. The motherboard in the Titan FX machine will run all 940 pin processors, however only the 200 and 800 series Opteron processors will run as Dual processors." AnandTech just tried to benchmark the Titan FX system with 2 FX51, and while the system worked, the boot screen only identified ONE CPU even though two were installed. Oddly, the few benchmarks we ran were higher than single CPU, but not at the levels we would expect with Dual Opteron chips.