when u switch on ur pc, hit del button or whatever you have to press to enter the setup BIOS menue, then navigate to PC Health Status, down there you'll find CPU fan clock speed and smart fan option... choose whether to enable or disable them.
I had just received that same notice when starting up my computer. A wire harness was keeping the fan blade from turning. I was just inside the case adding a drive and didn't check that before closing it up. After getting that message, I could see that the fan wasn't turning. My Antec case has a plexiglass window on the side.
I simply moved the harness over.