Question Different idle power consumption on multiple Geforce RTX 2080Ti machine

May 16, 2020
I recently built a machine for doing deep learning with 4 Geforce RTX 2080 Ti and am using a HERCULES 1600W 80 PLUS GOLD® PSU. The GPU has two power ports and the PSU comes with two different types of PCI-E cables. The first type connects to a single port on the PSU and splits into two connecting ports, so with this type, I can connect both of the GPU ports to a single port on the PSU. The other type is the normal one-to-one type, which needs two ports on the PSU to connect to both the GPU ports. My first question is if there is any difference in which cable I use for these connections? Right now I have connected 2 of the GPUs with the split cable and 2 with the one-to-one cables, and I am seeing a difference in the idle power consumption in these methods. The GPUs with one-to-one connections use around 20W of power whereas the ones with the split cables use around 2W when idle (all GPUs are in P8 performance mode). Any idea why this could be happening and could this have any effect on the system?