I've been running 4x GPUs (3x 1070s and 1x 1070Ti) for days with 1.20 and had no issues. I had some strange errors with 1.21 with low hashrates and so went back to 1.20.

For 1.20 I ran with intensity 21 and 120watts on all 4 without any issues. memory was at -500 although some said to do -502 which im not sure why. And core voltage is up to 140 I think, ill have to double check on that.

Each card is running between 61-65C and I've yet to see it crash on 1.20. My total wattage is around 500-535 which I'll take anyday over 850watts. Electricity these days are freakin expensive in California.

I've ran this setup on ubuntu 16.04, 18.04 server and desktop variations, mint 18 and now running it on mint 19 and it's solid. I'll try 1.22 and give an update in about 24 hours.