a1 and a2 ram slots not working: Dell R740 not recongizing memory module in slot A1. Dell PowerEdge R720 and R720xd Owner's Manual | Dell Rwanda. Correct slots for dual channel? | Overclockers Forums.
Both A1 and A2
slots work individually, or even combined, but then the mobo says that I should not plug both chips in the same channel and refuses to run since this is not optimal configuration.
poweredge-r720 | Dell PowerEdge R720 and R720xd Owner's Manual | system-memory ... channel 0: slots A1, A5, and A9 channel 1: slots A2, A6, and A10 channel 2: ...
One of the suggestions to fix the problem was that I had my ram in the incorrect slots. I think I put it in the correct dual channel slots, but they were only marked A1,A2,B1 and B2, so I could be wrong.