Hi,
Mach4 is not a power hungry application, just about any PC will run it fine.
I bought a dual core Atom based mini-ITX PC some years ago (still running Mach3/parallel port at that time)
with 32bit Windows 7. It uses onboard graphics and as the saying goes...'couldn't pull the skin of a rice pudding'.
I've been running that same PC with an Ethernet SmoothStepper and Mach4 for five years, all without problem.
The only time I notice that the (guttless) little Atom struggles is if I load a largish program, say 5-10Mb, it will take
a minute or so to load and draw the toolpath but thereafter its fine.
My advice is that unless you regularly load large 3-D files say, don't waste your money on a powerful PC, you don't
need it, a cheap and cheerful little PC like my Atom will run just as accurately, smoothly and every thing else.
I haven't tried one of these, but they appeal to me, 4G RAM, 64G eMMC, Windows10 Ent with runtime activation for $209:
https://www.dfrobot.com/product-1585.htmlThere are a number of these small single board PCs out there, and if they run Windows10 (ie all of them) then they'll run
Mach4 no sweat.
Craig