ive personally not had much success with PWM fans for cases. You can only really set them to ramp up and down with CPU temperature, which (for me at least), causes issues when my GPU is under heavy load and my CPU is hardly doing anything. My GPU gets starved of air because the fans wont ramp up.
I recently bought a fan controller, the aquaero 6, that will allow me to control my fans based on whichever component is hotter so i shouldn't run into this issue anymore. If it doesn't work out (i should have no problems), oh well, i have fun tinkering with my PC anyway haha. Plus i have an awesome tool if i ever wanted to try watercooling at some point... which i have no current desire to do.