OP already uses two separate PCIE cables. The GPU has however accepts three plugs so one cable is daisy chained.

Try with 3 PCIE cables to see if that solves the problem.

If you must go with only two then switch the plugs around so the daisy chain ones plus into different slots. I don’t think power draw is spread equally on all three. Assuming your PSU is high quality and should be able to handle the load.