I worked out I can't hear my air cooler fans at all if they below 1050rpm, I can't keep them below that forever as need them to be able to cover CPU temp increases, and keep package temps around 50c, but its handy to know where the silence mark is.
Every day since installing the Noctuas, I have had to adjust the curve somehow. That makes sense to me, since I only had them in a week, and temps vary every day. Eventually I will have one curve that matches most circumstances... maybe.
I should save a profile to use in summer and one for winter. Mainly as I only have so many points on the chart I can assign, so I expect the curve will be different in summer to winter.
I only hear the intake fans when they get over 600rpm, so I have them running just below that except when CPU temps rise as well. Its not them so much that needs the adjustments. They doing a good job keeping my GPU and nvme temps low.
The next few days are all over 33c outside so I expect I will hear it more, but on some hot days its just easier to leave PC off for a few hours so I can live in the same room. Might do that soon.