LOL Not that it helps the cause much, but I was using a 15' printer cable with one end cut off and the wires right into my drivers (no BOB), now I still have no BOB but I'm using 2 6' cables plugged into each other, so 12' with a connector in between, then wires stuck into the female pins of the cable...
If the motors are on but not moving, it sounds like you're just not getting the step signals to the drivers. (even with no DIR signal they will still move with STEP. Just in 1 direction.) If it was degraded signal on any of the lines, I'd think you'd at least get some movement. So far I've been using a laptop for the past 3 years, as I haven't been able to get any desktop to work reliably. I guess I'm the anti-normal.