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.
RTX 2080 SUPER total graphics power is rated at 25W higher than the original 2080, and that played out pretty well in our testing, with our system drawing an extra 29W with the 2080 SUPER. That's only 10W less than the 2080 Ti, however, so it is not as impressive in terms of overall power efficiency.