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.\
Total system power draw is just under 210W for this Challenger 8GB, a small increase over the Pulse 4GB model. In terms of AMD's own products, this marks a noticeable improvement over the RX 580 – total system power draw is down almost 70W, despite the 5500 XT 8GB also proving the faster card.
Then again, AMD still has work to do to catch Nvidia in this regard, with total system power draw roughly 55W less with 1650 SUPER, and 30W less with GTX 1660.