Ok just looked and there is nothing connected there on mine, have just read the manual as well on Arc Euro's site and it says 5v on the enables actually disables the drives and if you dont want to have that feature just keep connected. So connecting 5V would do no harm but unlikely it will help unless your drives are the opposite.
I am wondering, do you have the dip switches set correctly? If you have the max microstepping set your motors may be moving just that slow you dont see anything. For example if you had the dips et for 51,200 micro steps it would take 10,240,000 pulses to move one rev, if you have Mach set to the default 2000 steps per inch then that would 5120 inches worth of pulses to move one rev of the motor. If you have the default velocity, 120IPM then it would take the motor 42.6666 mins to do a rev, in other words kind of slow
Hood