hold up, I have used 2 of randys encoders and if you dont hook power up to it than its a no go.. Im not doin it for fun am I? its and input not an output right?
blegh well its been a few months and its cool so.....
Not a good idea! In all honesty, if you are using the 5v supply from the PC, it's pretty much the same one that's connected via the PS/2 port. So it
shouldn't hurt anything....but it's not necessary to do that and I'd advise against it.
So no, it's considered an output, not an input, and yes, you are doing it just for fun

I would disconnect it to be on the safe side.
RandyT