For PowerEdge C-series servers use the attached excel tool to decode the SEL RAW data to figure out which DIMM slot is/was having problem.
How to collect the RAW SEL data:
Example one of SEL record:
SEL Record ID : 0021
Record Type : 02
Timestamp : 02/08/2012 12:40:58
Generator ID : 0021
EvM Revision : 04
Sensor Type : Memory
Sensor Number : 60
Event Type : Sensor-specific Discrete
Event Direction : Assertion Event
Event Data : a1ff14 (This is the Event Raw data you need to fill the 6 bytes into cell#B2.)
Description : Uncorrectable ECC
Not Applicable
Not Applicable