I have the following system:
Asrock 880GMH/U3S3 AM3 running a Phenomx4 975BE with an Arctic freezer 7 Pro Rev2.0, PSU Corsair CX600 and 1 slot Corsair 4gb RAM DDR3 1600mhz.
I updated my bios from 1.40 to 1.70 due to the thermal issues shown on H/W monitor in bios:
heat of CPU
no possibility to set RPM of my CPU fan.

So,after udating the bios I solved the first problem: before my CPU was running at 50 degree in idle, now with new bios 32 degree.
But I got a new one: as soon as I installed the new bios my motherboard stopped working (no possible to boot windows), no display vga, I saw also the lights of Ethernet were off.
Finally I changed slot of my Ram and the computer started to work. (this is very very strange).
I still don't have the possibility to change RPM of cpu fan and also chassis fan.
Cpu fan is working between 1779/1854 in idle
In H/W monitor (BIOS) nothing change if I set FULL ON or AUTOMATIC MODE both on CPU fan or Chassis fan.
In CPU Config I tryed to change value on cool'n'quite from enable to disable,sec virtual, cpu thermal throttle but those values don't make any difference, don't affect directly the RPM speed.
I start to think the this motherboard (the first one that I have purchase from ASRock in my life) have some issues, I NEVER had problems with Asus.