www.ubuntu.com, 1200W is definitely too little.
850W for mainboard and 3x cards.
850W for remaining 3x cards.
Do you recommend getting a better psu or does changing to Ubuntu do any difference regarding the Power? Cant imagine that.
But my wattman says 950 when they are all on 100% Power target, that is for the whole rig...
it's like redlining your Porsche, you can go there but don't keep it there. At 950W your 1200W PSU is probably about to kick the bucket.