Chris_B151,   It does sound like a board issue with the fan error remaining in the same slot when the fans were swapped out, but what I suggest is to remove the fan in slot 3 and inspect the slot for debris or damage. If not then it likely is a board failure for the slot.    Let me know what you find.    
Hello Anyone got any ideas ref this one at all?  PowerEdge VRTX will not power on, display states Power on aborted.  The CMC starts but the front control panel shows error with fan 3 reading 0 RPM.  I have swapped a fan from another slot into slot 3 and I get the same error.  The swapped fan does not spin up.  The fan from slot 3 spins up OK in its new slot.  So it looks like the fan is OK. I assume this points at a mainboard issue / failure but I wanted to see if anyone had any other ideas?  This VRTX has been sitting powered down for a couple of weeks, but was working 100% prior to this with no errors or alarms?  I have power cycled the unit and reseated the fans a number of times. Thoughts / suggestions?
PowerEdge VRTX will not turn on - fan 3 0 RPM