Undervolting using nvidia-server?

In Linux,
Only 1 of my 3 GTX 1060 cards are supported in the nvidia-server, for changing GPU and RAM speed.
My MSI graphics card was supported.
Zotac and PNY not, and neither do my 1050 or 1030 show any frequency adjustment settings, nor have fancontrol.

EVGA’s precision XOC under windows was able to recognize the cards and modify the GPU, memory, and FAN speed on all those cards (save for fan speed of the 1030 which is passive).
But for Linux, I’m limited to the options nvidia-server has to offer.

I enabled coolbits.

Is there also a way to implement under/overvoltage for GPU in nvidia-server software?