The Asus spec for this board seems fairly clear. There are two groups of controllable fans, the first group includes the CPU and OPT_CPU and the second group three chassis fans. So five controllable fans, but in two groups. I can't see anything from Asus that suggests that each fan is controllable independently. Bearing in mind that up to five PWM fans could be used, the Asus arrangement is something of an advance on using a PWM fan chain and the associated cost of a PWM splitter cable. And the BIOS controls in my opinion are pretty good by any standard, and can be supplemented by Fan Xpert if required.
If you wanted to control an individual PWM fan I suspect it could be done with a Zalman PWM Mate or a PWM resistor cable.
My last motherboard was ALOT cheaper than this motherboard, i had a DFI x58. This had 6 fan headers and 5 were independently controllable. I have always had this with previous motherboards and all my previous asus motherboards had all independent fan control.
I think this is actually abit lame by asus to be honest and a step in the wrong direction compared to the past.