Random observation:
The M4A785TD-M EVO apparently ramps the speed of the fan connected to the chassis fan header up and down with the CPU fan speed, even though the chassis fan header is only a 3-pin (non-PWM) header. The PWR fan header does not do this (runs at full speed all the time). Until I figured this out, I actually thought I had a defective fan!
Contrast with the M4A88T-M (a very similar board), where only the CPU fan changes speed with CPU core temp (both the chassis and PWR fans run at full speed all the time).