My CNC pro card has been a bit of a problem from the start. Mostly overheating or loosing its way, even converting to inches halfway through a job. So against all advise, I purchased some of those cheap drivers from China, Aus$140, did all the recommended modifications, and installed Mach 3. I have just finished running the initial tests and can not believe the sound of the motors. They positively sing. Ran some tests for missing steps, ran a test cut for over 1 hour, not a sign of overheating and the steppers sound so good! Really happy so far. Next test is to start turning a nice piece of jarra into chips.