well you would be correct if you only run the 2pacs and compacs.
if you run other mining software windows 10 and windows 7 on a pc are fine.
At the moment I run cgminer and nicehash
this give me 1 compac 1 2pac and the cpu mine xmr on the same pc.
the cpu xmr adds about 10 or 15 watts ands net a very small profit.
which means the 1 pac and 2 pac cost no extra on the mobo or cpu power use.