I have put together a new Eth mining rig, it's currently has 4 3070's. Problem I'm having is with 1 GPU in, I get 52-62 mh/s depending if overclocking, when I put an additional GPU in it says they are doing roughly 27 mh/s each, 3 GPU's in it says I'm doing about 18ish mh/s each, and 4 in I do about 12-14 MH/s each. I don't understand but it seems like with every GPU I add, my MH/s cuts in half.
Any help would be very much appreciated.
CPU: i-3 10100f
Ram: 8gb @ 2666 ddr4
Windows 10
GPU's: 4 EVGA ultra gaming 3070's
PSU: 2x 750w Corsair CX750m
4x risers