Probably nothing. Creating the masks needed to mass produce chips is expensive so manufacturers will often use the same chip for multiple products. The M3 may b

Probably nothing. Creating the masks needed to mass produce chips is expensive so manufacturers will often use the same chip for multiple products. The M3 may be used by higher end products (i.e. enterprise drives) or it may just be the vestigial leftovers of some feature which was planned but didn't ship.