[HomeCNC]

It would seem that you have tried more than enough computers to rule out the LPT port. Unless you somehow have the wrong LPT port called out in the software. Some can use two ports.
Oh and just to cover it. Make sure the LPT port is turned ON in the PC's CMOS setup.

That leaves two other things to check. The wiring and the config of the step and direction software.

Let's just look at one G320 drive and call it the X axis drive.

Look at the picture below and re-check your wiring. Where are you getting the +5 VDC power for the Gecko drive? (I use an external wall wart).

To charge the G320 just jumper the "Err/Res" to the "Enc +" and hold this for a few seconds. To dis-engage the G320, jumper the "Err/Res" to the "Enc -"

Double check your software that pin 2 and 3 are set correctly. If you are using Mach 1/2 you will need to define Jog keys.