Dell PowerEdge R620 Owner's Manual page 41

The system contains 24 memory sockets split into two sets of 12 sockets, one set per processor. Each 12-socket set is
organized into four channels. In each channel, the release levers of the first socket are marked white, the second socket
black, and the third socket green.
NOTE: DIMMs in sockets A1 to A12 are assigned to processor 1 and DIMMs in sockets B1 to B12 are assigned to
processor 2.
Figure 15. Memory Socket Locations
Memory channels are organized as follows:
Processor 1 channel 0: slots A1, A5, and A9
channel 1: slots A2, A6, and A10
channel 2: slots A3, A7, and A11
channel 3: slots A4, A8, and A12
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