Best type of fan for sucking air through a small hole?
A centrifugal fan should be able to push maybe 300-500 CFM through that hole, it will be fairly noisy and will probably draw 200-300 Watts depending on the size. Maybe something in the 1/6-1/4 HP range. However fans generally don’t do much when they are taking in relatively warm air to begin with. A fan will help a bit but if it gets hot where you are drawing the air from it probably will not be satisfactory. Usually a server room using that much power would be cooled by refrigeration.