I think I did not claim that Asus in general does not support 3 pin fans any more. But both my P67 Sabertooth and the P8Z77-I deluxe do not control 3 pin fans when hooked up to a 4 pin fan header. For the Sabertooth I have to admit that it also has at least one 3 pin fan header which allows for fan speed control. But that's it. And the P8Z77-I deluxe has only two 4 pin headers (CPU and case) which are both PWM only.
I had defined profiles both in the UEFI and in Windows (Asus Fan Xpert). The 3 pin fans kept on running at 12 V. Once the Phanteks PWM adaptor was in place I could clearly hear and see the difference. But I am glad that you guys did not have any problems with your mainboards whatsoever.
I have attached two pictures from Fan Xpert, 1st picture shows on the right hand side that I was able to perform a test on the CPU Fan which is a PWM controlled fan and the 2nd picture shows that Fan Xpert does not allow to perform a test on the Chassis Fan which is a 3 pin fan.
