Hi,   Have you tried updating the iDRAC/LCC and BIOS to the latest and check if resolves the issue? Since slot A1 having issue, try this. Remove both power cables, press and hold the power button. Then remove all components accept the below and try to do the diagnostics, if you have the same issue, you may need to replace the main board.   •Risers•CPU1 (swap CPU2 with CPU1)•Heatsink for CPU1 for prevention of overheating•1 DIMM for CPU1 (swap any available DIMM with A1)•Power supply•Control panel•Motherboard•Power distribution board   Hope this helps clarify your doubts.  
My R410 is rebooting intermittently. It does this even when in diagnostic mode running MpMemory test. I get this error when going into diagnostic:Message PR1: Replaced part detected for device: DDR3 DIMM(Socket A1) I have changed the dimm for A1. I have also unplugged the power & hold down the power button for 30 seconds before starting normally. Both did not resolve the issue. Is there anything else I can do? If indeed A1 is faulty, what are my options? The server have 2 CPUs, 8x8GB dimm.  
R410 Memory slot issue