The curve depends on your fans. I use fans that spin up to 2700 RPM on my H80i and set the reference temp to the H80i liquid temp for a smoother change in fan speed.
Depending on your CPU point 1 should be the starting fan speed (usually 800 rpm) and the temperature should be about 25c. Point 5 should be should be about 60c and the fan speed should be the max speed your fan support (maybe 2700 rpm). Then adjust the temperature and RPM settings in the middle to balance temperature VS noise level (if you aim for a quiet PC) Ill post a picture of my setting when i get home tonight.