This morning I felt the top of my computer was a bit toasty. So I fired up HWMonitor, found that my CPU temps were 41C even though nothing was using it! I looked down, and saw that all the case fans were off! HDD temperatures were at 50C...
I have 3 case fans hooked up to that fan controller on the Corsair Graphite 600T - a Noctua S12 and the two white LED fans that came with the case. Normally the fans spin even when the fan controller is set to minimum, but now they only spin when the fan controller is set to maximum! I unplugged two fans, and the third fan came up happily again on minimum.
I only connected one Molex connector to the controller, so I don't see how anything could've gone wrong there. Do fan controllers fail in this fashion? Or could something be sucking the juice away? Say, for example, a slightly faulty USB port that I once plugged a moist USB stick into?