I've tried adjusting the sensitivity of the controller, only to discover it was still unresponsive

Ofcourse; Everyone's hardware is different so it's hard to pinpoint the issue just by that.

The only electrical cable in direct touch with the gamepad is the wire of my Logitech G11 Keyboard.
My monitors are both without a standard and all it's cables are put away in the arms of my monitor stand (Where my controller is plugged in with extra AC power)

I'll look into the issue of the PCI usb card once I get the change to do so,
this is something I sadly can't check right now.
However; Since this desktop was a hand-me-down (which was, in all aspects better than my previous laptop) I did get the information the bottleneck of the Desktop was it's motherboard. (Dualcore) ((it seems, prehistoric stuff))

I don't want to point fingers, not at all, never was and never will be my intention.
I'll try recallibrating again, I'll hope others will attempt to have a look at this too, but thank you for pointing me in a direction of a possible solution!