Efficiency
We don't want to make too many direct comparisons between test results gathered from The Beast because each PSU was run under different loads corresponding to its individual specifications. However, efficiency is important enough to make an exception. Here we've graphed the efficiencies of each PSU at 25, 50, 75, and 100% capacity to see how they stack up against each other.

Our efficiency results are pretty close overall, but there are a couple of interesting trends worth pointing out. Notice how the efficiency spread is only about four percentage points with our 50 and 75% loads. That spread grows to closer to 10 points under 25 and 100% loads.

Lining up the competition on a single graph further illustrates just how close the contenders are, particularly in the middle of our load spectrum. The BFG ES-800, Zalman ZM-750HP, OCZ EliteXStream, and PC Power & Cooling Silencer stand out as particularly good candidates from an efficiency perspective. The BFG and Zalman units boast higher efficiencies at lower load levels, which is important if your system spends a lot of time idling, while those from OCZ and PC Power & Cooling fare a little better when pushed to their limits.