Hi, Tried with Gigabyte RX 570 4GB 13 cards rig. Undervolting seems not working (used 900mv). Power consumption is fluctuating between 1200w and 1900w continuously. Hashrate is also fluctuating between 200 Mhs and 366Mhs. GPU 0 is always staying at 17 Mhs, Others getting at upto 29.10 Mhs. Same results without Undervolting as well.
X server is not starting. Better to Disable this service by default because its taking lot of time to get the system fully started.
I have a lot of confirms now that it's working.
Did you set DPM state or only 900mv?
If you have power fluctations i would search for other reasons.
X server is starting just in 5 seconds, you should connect display to external GPU in 16x slot, not to internal GPU.
X server is really required for Nvidia cards so it will not be disabled.