ECC RAM protects against bit flips (a bit changing to the wrong state). These can be caused by electric or magnetic interference. A pixel of a picture suddenly having the wrong color because of a bit flip is not that bad but some day an important file might end up corrupted because of one. I want to sleep well at night not having to worry about silent data corruption so ECC RAM it is. See here for more information: https://en.wikipedia.org/wiki/ECC_memory