-Core i7 6700k
-Asus Z170-A
-16 GB DDR 2400
-Asus GTX 970 STRIX
-Fractal Design R4 (reused)
-2x Stock Fractal Fans
-Scythe Cooler with Noctua NF-A15
-Seasonic 460 watt fanless
My old system was pretty quiet but I used a Gigabyte motherboard with poor fan controls. I just undervolted my fans instead of using the bios to control it based on temperature. I bought the Asus motherboard because I've heard good things about the fan control and want to fully utilize the functionality.
From what I've read I should go into the bios and run the Q-tuning ability to get the min and max speeds of each fan and then adjust the curves. How should I adjust the curves to get it as quiet as possible? The SPCR 4k guide shows the fan curve set flat all the way and jumping to max at 75C

Is this for the case fan? Won't it be better to set a gentler sloping curve rather than jumping to 100% at 75C?
How should the CPU fan curve be set up?