ASUS Mo Utility Suddenly Doesn't Recognize Fan

ASUS board, 1 year old, has the Asus Probe Utility for, among other things,
monitoring the fans, incl. the PS fan, the CPU fan, and one of my 3 case
fans.

All of a sudden, it says that the chassis (case) fan isn't running, and is
giving an audible "bonk" warning sound. But the fan IS running.

It's plugged in to the board.

What's wrong, can anything be done to fix this?

Thanks!

I hate to turn the utility off, but don't want to listen
to that bonking all the time, incl in the headphones.

the asus probe reports a fan problem when a fan is either running to slow or does not register at all (and therefore is considered stopped)

if the fan uses a 3-pin connector that goes into the motherboard, the yellow wire is ised to detect the fan's speed. you have to make sure that there is, at no point, a loose electrical connection, or one that is blocked by dust.

you can disable the alert in your bios, and probably in the asus probe utility as well.