I have a Chinese cnc that I have retrofitted with a set of motors, cables, and G540. I had a hobby cnc controller on it, and with that setup I could get about 30in/min. When I upgraded to the G540 I thought I would get higher speeds. I can get the same 30 in/min but when I move up speeds I get motors stalling (like really whining not just loss of power). It is random. I can physically push against the gantry with all my weight at 30 in/min and it will not stop. But if I bump speeds unto 40in/min it randomly stalls.

I have mach3 and have tried just about everything I can find online. Does anybody have suggestions?

Thanks