We measure system-wide power draw from the wall while the card is sat idling at the Windows 10 desktop for 30 minutes. A reading under load comes from running the 3DMark Fire Strike Ultra stress test 20 times.
As for power draw, I was slightly surprised to see this Gaming OC pull less power than the Founders Edition, but the margin proved to be just 2W so definitely within margin of error for a system-wide power consumption test. In any case, it's basically the same as the other 2070 SUPERs, with all three cards pulling with 10W of each other.