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.
Given both the Gaming OC and Founders Edition share the same 320W TGP, it's not a surprise to see real-world power draw was basically identical between the two, hitting just over 300W in Cyberpunk 2077.
Combining the power draw values shown above with the performance data, we present performance per Watt for each graphics card tested:
That also means performance per Watt is identical to other 4080 Supers.