You can't.
As you can do it for the RX470/480 by patching the 'polaris10_smc.c' drivers (works perfectly fine for my rig), it should work with the RX570/580 too.
Unfortunately I don't have a RX570/580 and therefor can't test.
Cheers
Andy
Hi. I did the polaris_10_smc.c patch and it's working perfectly. However, on some rigs 818mv works for 4 cards and not working for the other 2. So, I have to raise it to 850mv for all cards in rig, which is really a waste.
Has anyone found a way to downvolt GPUs individually? Looks like the hwmgr structure that's being passed to the polaris_get_dependency_volt_by_clk function contains card index information, so we can use an array instead of a fixed value, but I'm not really that much of a programmer to dig that deep.
I am also a bit scared to do modifications and try them in a rig worth $1500. ))BTW, it's funny, this hack is dated 2016, yet the latest amdgpu driver (I have 17.40) still does not process core voltages the way Windows does. I wonder why the AMD software engineers never fixed it.