I had a 2060 super SC ultra, and the fan curve control worked fine, the curves I created responded as they should. Now I got a 2070 super XC Ultra and when I try to do a corner it works at first and then the fans get out of sync and the fans start toggling between 0 RPM and the RPM they are supposed to be running at, at first I thought it was just a tuning error software, but I kept looking at the fans while this problem was happening and it was noticeable how they slowed down and accelerated.
 
At first, they only work while the curves have points set to values above 20% fan speed, after a while they get out of sync, but if you directly set the curve points of the fans below 20% of the fan speed, they immediately get out of sync and begin to alternate between 0 and another rpm value.
 
The only way to keep the fans from getting out of sync and still working is to use the preset curves provided by the software, such as aggressive, quiet, stealth or custom or put them in automatic mode.
 
With the 2060 super I had no problems, and it was possible to set curve points for values below 20% without the fans taking strange values