sometimes you have a 12V supply to work with, sometimes you have a 24V supply to work with. 24v is common in some comm. equipment IIRC.

check the specs of the fan. there should be an voltage operating range. the minimum voltage in that range is probably the minimum voltage needed to get the fan to start spinning. if i recall correctly ...

If you're looking for options to save while staying cool in the Michigan summer heat and air conditioning isn't an option, a box fans in your windows may bring some relief. The box fans consume less ...