All the fans are plugged into headers on my motherboard in the following config:
2x CPU heatsink fan (3-pin) -> 3-pin Y-splitter -> MB header 1
Front two intakes (3-pin) -> 3-pin Y-splitter -> MB header 2
Bottom intake (PWM) -> MB header 3
Rear exhaust (3-pin) -> MB header 4
Then I use the Asus Ai Suite Fan Xpert 2 module to set a fan curve graph for each fan (bound to CPU temperature) which ramps up the fans quickly as temps rise, and then lets them slowly spin down after (to prevent rapid spin up/down which sounds annoying). The Fan Xpert 2 software is one of the main reasons I paid more for the P8Z77-V Pro instead of the Gigabyte UD5H or ASRock offerings.
I was letting all the fans full turn off when CPU temp is under 35C, but noticed the CPU and motherboard temperatures were slowly building up over time and wasn't comfortable with that. I now have the fans spin down to their minimums which is pretty much silent. The only slightly annoying thing is the stock 550D case fans only seem to provide a 1000rpm minimum according to Fan Xpert 2, while my CPU and PWM fan can go down to around 400rpm which is truly silent. Might replace the stock 550D fans at some point if I get keen.
Thank you for sharing your setup.
I didn't know that Asus mobo has better fan software. It sound much better than my ASRock.
Just to let you know, the stock fan from 550d can go lower than just 1000rpm.
At least according to my ASRock's Extreme Tuning Utility. When I set the fan to target level 1, the fans are spinning on around upper 300 rpm, closer to 400 rpm.