Quote Originally Posted by JOGARA View Post
Isn't there a way to dump excess power coming back from steppers?

Like resistors or something.
Unfortunately not. There are two main problems with the switch-mode PSUs in this application, although they are great and very cost-effective elsewhere. One is the back emf issue as mentioned, while linear power supplies dump excess power into the smoothing caps (one way to look at it, anyway). The other is that linear supplies are much more tolerant of peak overload. A switch-mode supply tends to hard-limit, maybe even shut down temporarily, if you try to draw more than rated current where a linear supply output will tend to just sag a bit which is not usually a problem. If you are now looking at Mach3, you might also consider something like a UC100 or UC300 with UCCNC which is looking like an attractive option these days. Still need a break-out board but it's a better option than using Mach3 and parallel port.