Did you start using MSI Afterburner or something? I got similar issues when Afterburner is running, since setting the fan curve there is extremely finicky on my syatem, for some weird reason. It either runs the fans at minimum rotation at all times, or seems to never turn them on at all for me and no matter whqt I do, it's impossible to fix. So I just left them running... it's not really any extra noise, and with how much power the card already eats, also not much additional consumption...