Can't adjust fan speed on my GA-P35-DQ6

All fans in the case and the one attached to the CPU cooler seem to be running at their highest settings. At least I think so. I built my PC about a year ago and from the first fire up, the fans have always been running at this speed. Even if I play a game, they never get louder or softer if I close it down and just surf the net. If I use SpeedFan, no tweaking does anything to the fans.

Any ideas?