Hashcat temperature control only works when one GPU used at a time?

[rsheasby]

Hey, so I've run into a strange issue with Hashcat v4.1 on Ubuntu 18.04. It seems that the GPU temperature control only works when a single GPU is used at a time. When enabling two GPUs at once, the GPU auto fan speed kicks in which is way more conservative and leads to much higher temps and therefore crashes.
I've just now tried upgrading to v5.1, but it seems the GPU fan speed control was removed entirely?

This is a dual R9 290 setup with AMDGPU-Pro OpenCL drivers.