Which molex connector?
Your cat been at them all?![]()
How you you undervolt with afterburner?
There was an issue with a few of the early rtx cards where the ram could become unstable at stock clocks and this would make the cards artifact similar to what your experiencing. By underclocking the cards memory with programmes like msi afterburner it was possible to correct this although it would mean a small hit on performance. You would just need to drag the memory clock MHz slider to the left till it shows say a -500 offset then hit apply.
How's the Gpu temps looking?