Title explains it all, I've had this system running since July and haven't had any issues. Just this morning I noticed the fan stopped spinning (glass window on case), and I tried a few things--eventually plugged the fan into CPU_Fan2 (was initially plugged into CPU_Fan) and it works just fine.
Any ideas? Seems to definitely be an issue with the motherboard but maybe I'm mistaken! And is there anything wrong with running it through CPU_Fan2 or will it work the same?
I agree. It would seem that the cpufan1 has failed.
If you are still under warranty, I think I would try to rma the motherboard.
Otherwise, since fan2 seems to work ok, I see nothing wrong with continuing.
The presence of fan2 is a bit of news to me, but I think it is a nice feature to accomodate those cpu coolers with a push/pull dual fan configuration. A motherboard will not normally start if there is nothing attached to a cpu fan header.
Have you updated your BIOS lately? If so, it could be that your fan settings were reset in the BIOS to disable fan headers until the system exceeded a certain temperature. You might want to review (and adjust if needed) the fan settings in the BIOS.