We use Nvidia PCAT to measure power draw of the graphics card only, with readings from both the PCIe slot and the PCIe power cables combined into a single figure. We use Cyberpunk 2077 (1440p) for this testing.
Power draw is higher than all the 7900 GRE cards we've tested, with the exception of the Nitro+, given the Hellhound hit 280.6W.
Combining the power draw values shown above with the performance data, we present performance per Watt for each graphics card tested:
That does mean efficiency is reduced compared to the reference model, but not in a significant way.