EDAC is when you see something like this in your logs:
EDAC k8 MC0: GART TLB errorr: transaction type(generic), cache level(generic) EDAC k8 MC0: extended error code: GART error
 What does that mean?
EDAC (Error Detection and Correction) subsystem report errors that occur within the computer system and were detected (and corrected if it was possible) by the hardware. The system with corrected errors can continue to operate, but with less safety.
 What to do?
Harvesting those events and reporting them can be a predictor of future uncorrectable errors. Preventive maintenance and proactive part replacement of faulty hardware can reduce the likelihood of the dreaded uncorrectable errors and system 'panics'.