Behind processor 2:   The numbers are also usually printed on the motherboard - in very small lettering next to the port.
Hello,  I have a PowerEdge 2650 that has a failed fan, ESM MB Fan3, according to the ESM logs.  Which fan is fan number 3 and where is that located in the documentation?  I've opened up another PE 2650 and took a look but I don't see any clearly marked numbers on the fans.  Any help would be appreciated, I'd like to know which fan needs replacing prior to opening up the server.  Thanks!
PowerEdge 2650 Fans - Which Is Which?