There's only 4 options for fan control. Manual (some led versions have auto settings) fan controllers, bios, motherboard software or SpeedFan. For some odd reason, that's the one area nobody is putting any effort into, whatsoever.
SpeedFan is great, when you finally do get it dialed in, which is possible by manually setting the specific fans on specific addresses to user defined fan curves (royal pain in the...).
Motherboard software is iffy, but has come a long way, Asus fanXpert being the best by a very long way. Very user friendly to orient fans and rpm for specific temps.
Bios, well that's as basic as it gets and pretty much usable by most ppl.
Manual controllers mostly fit to the optical bays, can be anything from sliders to knobs to led readouts with user programable settings. Usually harder to deal with, mostly requiring user input at different stages since they don't have operating fan curves. (led type can)
Your issue ties directly to the fan abilities themselves. Those corsair fans will only operate @ 60% - 100% or roughly 1700rpm-2800rpm ±20%. There's absolutely no way to get them 'quiet', which is mostly 900rpm or below. (Now you understand the stereotypes that claim aios are loud, Corsair has by far the greatest share of the market).
In order to get 'quiet' I'd toss the SP 120L's in the bin, and get some decent fans. Noctua, Phanteks, Nzxt, be quiet! Etc.