Just recently, there was a pesky failing fan inside of our controllers on a Xiotech Magnitude 3D 4000. A replacement part dispatched and when the controller was taken off line, it was difficult to determine which fan was “Board Fan 1” since there were no markings. In addition, the fan numbering could have started with zero for all we knew. After trial-and-error, this is the correct fan numbering schema.
In addition, the controller motherboard is a SuperMicro X6DH8/X6DHE-XG2.