ECC stands for error-correcting code, and it works by using additional parity bits to verify that the data read from memory matches the data that was originally written to it. Regular RAM has no such safeguard. If a single bit in a memory cell flips from a 0 to a 1, or vice versa, standard memory has no way of knowing anything went wrong. That corrupted bit just gets treated as valid data and passed along to whatever process requested it.
