Fan Noise
The ECS A770M-A is all passively cooled, so there is no fan noise. In the BIOS you will find a "SmartFan" option to control the CPU fan speed based on temperature.
Overclocking
Overclocking is quite limited on this board. The only memory timing that can be changed is CAS latency. You can adjust both CPU VCore and the memory voltage, unfortunately a CPU multiplier change option is not present.
We tried with both an X2 5200+ CPU and a 3000+ both could be overclocked to their respective maximum clocks. Testing beyond that to determine maximum HT speed was not possible because of the missing multiplier adjustment.
While overclocking is well possible with this board, do not expect any miracles from it. It is great for casual overclocking in the 0-25% range over stock, but not more I could say.