BG scrubbing will not hurt your system so I would enable it and if you get any slow downs or anything out of the ordinary then turn it off. If you are running a dual CPU system and you have ECC memory BG scrubbing is not required so play around with that setting to see what works best.
ECC Memory Scrubbing When the memory
controller enables scrubbing, memory is scanned periodically to check and correct hardware errors. Therefore, special care needs to be taken in order to avoid undesired ECC faults introduced by memory scrubbing.
Might want to just leave it off.
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