ecc and unbuffered is the same thing and ecc means error correction code and the ram has a little code in it that runs all the time and checks for errors ( mostly used in servers and some workstations ) and it usually cost more than non ecc

if yours is just a desktop then most times it will not need ( and some times will not work with) ecc also sometimes they state that the ecc is also edo ( extended data output ) which may not work either in a desktop

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