I would suggest that you don't even go there lest you fry your PC, EZ-B or both USB typically only supplies 500mA and even if that was per port (sometimes not) then you are still risking under-powering the EZ-B and risking burnout on the USB end. While the EZ-B itself might work, I doubt you could power much else.

If you wish to tie into the same PSU (assuming a standard AC fed PSU) then you could easily tap into one of the PS's 5v PSU sources as they typically have more amps to spare (possibly via a Molex or SATA power cable). Again, watch the total amp load supplied by the source (the power rail feeding the cables).

If the PC/robot needs to be mobile then look into a battery (12v) to DC-DC Power converter (12v, 5v, -5v, -12v) to PC and tap into that source as well for the EZ-B. Or just go with a laptop or mini ATX type PC that works off a single DC voltage (typically 12v) and again, tap into that as long as it supplies the needed amps.

Have fun and keep us updated

I can power the EZB with the Molex from the mmini itx power supply?

Thanks.

The EZ-B can take up to 18v... but add a small fan to cool the regulators. Looking forward to seeing some details and pics.