could a bad power supply cause unstable polling rates for the mouse?

Solution
I would suspect drivers (mouse and usb drivers), the program you are finding the polling rate issues in (if other than desktop) and then the usb port itself before the PSU. If the PSU was the culprit you would probably see more issues than just the mouse polling rate.

Dom_79

Distinguished
I would suspect drivers (mouse and usb drivers), the program you are finding the polling rate issues in (if other than desktop) and then the usb port itself before the PSU. If the PSU was the culprit you would probably see more issues than just the mouse polling rate.
 
Solution