How to force max rpm on stock AMD dual core fan?

I have a AMD dual core 3800+ that happily runs up to 2.55 ghz (255x10), however, there is a fan-related problem that sometime causes instability: the stock AMD fan is a variable-speed type, with the max rpm of 5000. The fan speed supposedly ramps up in accordance with CPU temp, which it does most of the time, but there are occasions when the fan speed is stuck at 3000 rpm or so even though the CPU temp is close to 60C (which normally calls for the fan to operate at the max 5000 rpm). Naturally, my CPU craps out with such inadequate cooling.

My question is a simple one: is there any way by which I can force the fan to always operate at the max rpm regardless of the CPU temp? My motherboard is ASUS AN8-SLI Premium (rev 1.02), and I’ve tinkered with all possible options in the bios menu, to no avail (ie. turning on and off “quite and cool”, etc). I’m thinking about dismantling the temp probe on the fan, but don’t know where to start for fear of damaging it.

Thank you for your advice in advance.