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.
Power consumption for the system came in at 291W, which is 14W shy of the RTX 2080 but 35W more than reference-clocked RTX 2070. How power hungry AMD's upcoming Navi cards will be, we don't yet know for certain – but Turing has Vega easily beat in terms of power efficiency.