So the board seems to be OK for beginning, but PSU seems to be the weak point.
Unfortunaly Platinium 1300W is actually not avaible on the market. So what second PSU would you use if power is real expensive and would you connect one or two GPU to it?
EVGA G2 1300 is pretty close to plat efficiency level, but availability is getting spotty since EVGA decided to move to their new G3 model (which IMO is a severe downgrade).
I've got some GTX 1070 models that have a TDP at 180 watts - "reference" is 155 not 150.
If you keep the TDP turned down to where the cards are pulling 150 watts or less, though, your 1200 should be plenty - the rest of the system isn't going to pull 300 watts.