I also have these 980 4g in SLI and had heat issues with the top card but I have found out what was causing it.
The weight of the power cables was pushing the PCB down, top heatsink was making contact with VRM1 heatsink, transferring heat to the GPU he...
The weight of the power cables was pushing the PCB down, top heatsink was making contact with VRM1 heatsink, transferring heat to the GPU he...