This does not, of course, make any sense. Any given memory cell will be read once per, say, millisecond, and the value written back. Once it has flipped once, t

This does not, of course, make any sense. Any given memory cell will be read once per, say, millisecond, and the value written back. Once it has flipped once, the wrong value will then be written back, and after that the wrong value is read back out and rewritten again, indefinitely. Errors are sticky, and accumulate. (Flipping back again is negligible unlikely.) With ECC in the refresh path, such an error could be corrected and the right value would be overwritten over top of the bad one. Then errors would not accumulate, but would instead be "scrubbed". Mainframe machines scrub their RAM. Disks too.