content: When my daily driver PC is on it's a wind tunnel in the case, so that isn't an issue, but I guess it should have an always on one pointed directly at it as well. So the demand with the Pi, fan, and SSD will need to be less than what the standby supply is. I just checked an old Corsair 750 left over from my Bitcoin mining days and it says 3 amps standby. I checked a couple of fans and they all say .16 amps@12volts with the 5 volt low speed option not listed. Even if the amp draw at 5 volts is double that would be .3 amps. And these were 80 and 120s I was looking at. According to this https://www.anandtechDOTcom/show/8747/samsung-ssd-850-evo-review/10 a Samsung SSD is the best for power usage- slumbering at 25 milliwatts and max 3 watts- so that would be .5 amps@5volts max. 1.5+.5+.3 = 2.3 amps total. I guess it really can be done using the standby power.