RT2.11 auto fan control problems w/ 4870x2 - T_min not static?

Hi, I'm having an odd problem with my 4870x2 and RT2.11 - I've setup auto fan control as per the guide over at [H] and I noticed that my T_min parameter seems to be creeping up over time (never down).

Here's what I set for auto fan parameters initially:

duty cycle min: 27
duty cycle max: 100
T_min: 50
T_range: 53
T_operating: 75
T_low_limit: 60
T_high_limit: 100

After a 60 second run of furmark T_min has already changed itself to 60 and T_operating is now 80, after a few hours of gaming I've seen T_min creep as high as 74 and T_operating sitting pretty at 94.

You can guess the inevitable result - after a day or so I might as well not even use RT to control fan speed and just let the card's bios do it since the temps are the same anyway.

Uh? Any suggestions?

 

Thanks, the self-adjusting curve is a little bit odd when you haven't seen the datasheet for the controller. I've been playing with it a bit more, I think I've got it nailed.

cheers!

ps: If anyone else wants to see the datasheet, I found it here.