Dell PowerEdge M620 Technical Manual page 22

Feature
Memory sparing (rank)
Memory thermal
throttling
For information on memory mirroring and sparing configurations, see the
Systems Owner's Manual
22 PowerEdge M620 Technical Guide
Description
Memory sparing allocates one rank per channel as a spare. If excessive correctable
errors occur in a rank or channel, they are moved to the spare area while the
operating system is running to prevent the errors from causing an uncorrectable
failure.
This feature helps to optimize power/performance and can also be used to
prevent DIMMs from overheating.
on Dell.com/Support/Manuals. Memory RAID is not supported.
Dell PowerEdge M620