vCPU, vPLL and vMEM Switch just add Voltage. Nothing else. 0,04V in each case.

OCP Switch increase OCP from 500A to 550A (no need for this on Water or Air)

PWM Switch changes the Frequency of the PWM (Voltage Regulation/Mosfets)
with higher Freq you got cleaner Voltage output but your Mosfets get hotter.
And even the Stock Freq of the PWM is a lot more than used on other Cards or Boards.

Extreme Cooling switch is useless on Air/Water