Power, Heat, And Efficiency
All manufacturers make great claims about voltage regulator efficiency, but ASRock and Asus bolster those claims at full load in the Z97 Extreme4 and Z97-A. Then again, a slight decrease in core voltage could produce similar results without causing a system crash.
Those reductions in power consumption are also seen in lower CPU temperatures, so lower full-load voltage does appear the most likely reason for saved energy. The question is, does this hurt overclocking?
Anyone really keen on overall performance charts can find one in this article’s image gallery. But the overall performance difference comes down to less than half of one percent. That means power savings translate almost directly into an efficiency improvement.
The Z79 Extreme4 wins the efficiency race, followed by the Z97-A.
Not exactly the most comprehensive review, but here is Asus' take on NICs: http://rog.asus.com/312772014/labels/guides/tried-and-tested-why-intel-ethernet-is-still-better-for-gaming/