From reading the user manual it appears that the CSE-731D-300B server case has a location for an optional front fan. I cannot determine what the location of the front fan is. Does the fan mount to move air over the hard drive trays or is it located below or above the hard drive trays?
After review user manual of the chassis CSE-731D-300B. I don’t see any where stating support front fan. There is no option supporting front fan on this chassis model.