4 pin fans will run well from a 4 pin PWM header ... not so well from a 3 or 4 pin DCV header.
Fans become audible at about 850 rpm..... 2000 rpm is loud... give a listen ... at 50% (1300 rpm) CPU load, I'm annoyed ... at 55% (1300 rpm) I wanna leave the room.... at 70% (2,000) , I start shooting real guns (at the fans) ..
https://www.youtube.com/watch?v=cTf0Vq1j4Ec
As for PWM ... PWM has its advantages and disadvantages. Among the latter:
a) Low speed hum or clicking
b) Cost
c) With Corsair PWM, fans loss of speed control with more than 2 or 3 fans on each channel
There is a way to get the best of both worlds and that is to use a PWM => DCV converter Fan Hub . They cost about $15 but you will save, at least $5 per fan. So with 3 fans, it's a wash.
You connect a cable from the CPU PWM header to the Hub. It takes the PWM signal and coverts it to a voltage signal... so you get all the advantages of PWM, mainly low end speed control but at lower cost and no humming or clicking
With say 2 fans on your cooler and 3 in your case... you can control all 5 fans from a single fan header. If the total amperage is < 1 amp (typically 5 or 6 fans), you don't even need to connect the SATA power cable to the hub.
Remember more fans at lower rpm is a lot better than less fans at higher rpm. But be aware, coolers sometimes have fans with specially spaces attachments
Maybe use these for case (no hub needed):
http://www.newegg.com/Product/Product.aspx?Item=N82E16835709041
And these on the cooler (PWM)
+ 20% off w/ promo code PHANTEKJULYBMA, ends 7/28
http://www.newegg.com/Product/Product.aspx?Item=N82E16835709037