How many fans does your unit have ?
My Powermodule has 4. They are 12V and draw 0.12A each
I hated the factory power supply (12V 1200mA) due to it's Euro-North American adaptor, so I replaced it with
this multi-voltage one rated @ 1.7A (1700mA)
I run it @ 7.5V
I tested the temp of the exhaust air and found it's no different than running a higher voltage, and the fans are silent enough
There's no harm in getting a supply with a higher amperage rating than needed (within reason) if it's a switching supply. It will adjust itself to the load