Is there a big difference in power usage between AMD cards and Nvidia? I've noticed a difference in my Nvidias from one manufacturer to another. I.e. my 1070s are MSI and my 1080s are EVGA. The 1080s are using 5 fewer watts (115 vs 120) for 14% more hashrate. This is actually a big deal for me, my power costs are Californicated.
I can't answer directly, I have no NVIDIA card. I've noticed an increase in power usage from win 10 build 1709 with 18.3.4 drivers to the 1803 build with 18.5.1. I was at 400-405W at the wall, after it was 420W. With the new hardware (X470 mobo, Ryzen 2400G, 8GB 2400MHz DDR4) I'm around 440W, Idle is 110W. That means around 110W par card while mining.
But I've not stop one card after the other to measure the individual power draw.
Right now I'm mining CN tokens, I burn 100 less W par hour.