The SR530 server supports up to six non-hot-swap system fans that
provide N+1 cooling redundancy. SR530 server models with one
processor include four system fans, and server models with two
processors include six system fans.
Configuration note: The SR530 FAN Option Kit (4F17A12354) includes
two system fans that are required for field upgrades that add a
second processor to the server. If two processors are selected in
the initial server configurations, two fans for the second
processor are derived by the configurator.
https://lenovopress.com/lp1045-thinksystem-sr530-server-xeon-sp-gen2#cooling