I'm not sure about power. The only way running these old machines is economical for me is because I have solar... that 2013 haswell machine draws about the same

I'm not sure about power. The only way running these old machines is economical for me is because I have solar... that 2013 haswell machine draws about the same power as a znver4 machine I built last year, but it takes several days to build a Yocto image the znver4 builds in two hours.