Motors just vibrating and not moving in one direction (no replies)

Hello all,

Im currently putting together a Prusa i3 and have hit a road block. The motors (all of them X, Y, Zs, and Extruder) will not step in one direction. They move back and forth erratically. I have adjusted the trimpots on the drivers in different positions from completely counter-clockwise to over half-way. Turning them up just causes more vibration and noise.

I got the Arduino 2560 and Ramps 1.4 (all 3 jumpers for micro-stepping on each driver slot) with A4988 stepper drivers in place. The thermistors read correctly and the heatbed heats ups just fine. I have currently running Sprinter firmware(I have tried Marlin and Teapot also with the same results). I'm using a Xbox 360 PS (203w).

I have also flipped the wires around for the motors (NEMA 17) but no change. I finally tested with a motor just sitting by itself and the shaft just steps back and forth.

Here are the drivers I purchased (http://www.ebay.com/itm/140967386673?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649).

Any advice on how to troubleshoot this issue would be great.

Thanks