Overclocking
Being a Black Edition chips gives us the opportunity of simply raising the multiplier until the frequency ceiling is reached. Putting 1.5V in the BIOS - which is about as high as we'd want to go on a 45nm chip, for long-term use - the processor was rock-solid at 4.3GHz (21.5x multiplier), kept in check by a budget Arctic Cooling Freezer 64 heatsink.
The already-high default speed means the frequency increase of 600MHz represents a 16 per cent advantage. It's needed, too, as the hike gives the 980 Black Edition parity with an Intel Core i5 2500K chip.