We measure system-wide power draw from the wall while running the 3DMark Time Spy stress test for 30 minutes.
Total system power draw is high, hitting almost 570W under load when using the Performance BIOS.
We also 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. This provides us with significantly more accurate data to work with as it is measuring only the GPU power, and not total system power which is a fundamentally imprecise measurement.
Then looking at graphics card-only power draw, we can see both modes are pretty close to their rated TGPs – the Performance BIOS averaged 417W, with a 420W target, while the Silent BIOS averaged 389W, with a 390W target.