Power, Heat, And Efficiency
Motherboards with the fewest on-board add-in controllers should obviously have the lowest power consumption, creating high expectations for low power use by MSI and Gigabyte. But looking beyond the obvious, differences in PWM design can also influence this test.
Gigabyte gives us the lowest idle power consumption, while MSI has the lowest full-load power use. This appears to mesh with MSI’s claims of superior PWM efficiency.
On the other hand, Asus’ power consumption is reflective of the company's claim that it's running all four cores at the processor's most aggressive Turbo Boost multiplier. As mentioned, you can counteract this by manually redefining the ratios for each core based on Intel's specification. If you don't, we can assure you that pushing higher performance costs additional power.
Gigabyte has the lowest PWM temperature, but its heat sink is also much larger than MSI’s. We only see that it runs cooler. We don't know exactly how much of that temperature difference is due to less power use.
Efficiency is a comparison of work to energy. Or, in this case, performance to energy. So, we need a compilation chart of performance results to calculate it. Asus’ performance-oriented settings put it 5.3% above-average.
That 5.3% performance gain doesn't end up serving as an advantage if you're worried about efficiency, given power consumption that's 10.6% higher than average. If you want to drop the P8Z68 Deluxe down to the levels achieved by some of the competing platforms, you have to do extra work to counteract the company's auto-rule (we'd perhaps suggest a UEFI toggle to turn this on or off, rather than manually remapping Turbo Boost ratios).
We used -1 in all of this chart’s calculations to form a 0% baseline, so that nobody could misconstrue it to represent better than 100% efficiency.