there is a way to controll the fan speed. im sure the firmware can too they just dont want to allow that but the way im talking about requires an external device that connects to the pwm wire that sends the signal needed to spin the fan up and or down. i got a bunch of them a while ago to control the fan speed on delta fans that have 4 wires (12v, gnd, tac, pwm) and they work great. since pwm fans need the 12v power to be steady all that is needed is to hook the pwn wire from the fan connector and connect it to the little module. the module isnt made to handle tons of power through it that delta type fans use but since the 12v and gnd are still on the main controller that wont be an issue. i tested it with the pre autotune s9's and was hoping to use it with s7's when it got colder but it turns out it wasnt that loud so it wasnt needed. i can test it with the auto tune firmware s9's too but im pretty sure it will work just the same. you turn the pot on the device to raise and lower the fan speed. one would be needed for each fan and maybe 1 can run both fans im not sure. i tested it on 1 fan at a time though.

http://www.ebay.com/itm/Mini-Fan-Controller-Use-on-4pin-PWM-Fans-Only-/251310564631?hash=item3a8346e517%3Ag%3AD8QAAOxyPc5R8pd&nma=true&si=xc7ix74cLY6XzIvXO35N657fd3U%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

that link is super old but thats the speed controller i used with delta server fans. it only shows a pic of the top side with the pot but the underside has the components that control the fan speed. they have other versions similar with a plastic shroud over it and should work the same way. i went with these because it was a simple design that attached to the fan itself instead of having a box hanging there. im not responsible for any wrong hookups though and even though its pretty simple to do make sure your removing and hooking up the right pin....