HP Apollo 4200 Gen9 - Page 108

Hardware options installation 108
b.
Install the fan in fan bay 5.
16. To enable fan redundancy in a dual-processor configuration, all 10 fan bays should be populated.
Obtain a Redundant Fan Option Kit (PN 806562-B21) and install five more fans in fan bays 6–10:
a. Remove the fan cage cover.