I think the noise problem you are referring to is Mach would shut down and go into an error in the middle of running a program for no apparent reason. If so, I resolved it by permanently jumping the reset button and disabling the limit switches in Mach. However I did not need to disable the home switches. I never could figure out why it would go into an error and it could have been some kind of noise in the system. After I did the changes, I never had anymore problems.