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 for 30 minutes.
Power draw is the lowest from any 1660 SUPER card, which makes sense as this is the slowest-clocked card, while it also has no LED lighting which can make a slight difference to power consumption.