Will it run without the fans plugged in? Because, if the S4 can run without the front fans plugged in, I can live with <65C and reduce the noise by half!
Edit: Or even switch the rear fans to the Deltas.. wondering if it will work... hmm....
I believe so, yes.
I tried the Delta 120 mm 5500 RPM PWM TFC1212DE the signal is reversed, slows down when it is supposed to speed up.
Would still be sufficient, only need 2500-3400 during sensible ambients.