I know on my Asus P9X79 Pro the cpu fan speeds change based on temp. Tho I am using 4 pin fans that I bought seperately and replaced the ones on my cooler with.
I pulled up the Asus P8Z77-v pro manual on the asus website. In chapter 3 it indicates you should be able to change the cpu fan speed... but only if you have QFan enabled. It then lists a few settings you can choose from and what the results should be.
It should be on pages 3-29 and maybe 3-30. You probably already knew this.. I was trying to be helpful and likely failing. Next week I'll have an Asus Z77 board to work with and get some hands on. Always liked them for their fan controls more than anything.
*edited* to remove an error and add the manual pages.