Does the MotherBoard "GigaByte GA-MA785GT-UD3H" support unclocking cores of CPU "AMD PHENOM II X2 550" ???
Does it need additional cooling or new fan?
The motherboard has a SB710 and the BIOS has ACC, so the motherboard is capable. Whether the chip unlocks or not is a gamble. I had two Phenom II 550s and only one would unlock to B50x4.
Here is the Core unlocking guide for a step by step if you need it:http://www.overclock.net/t/535501/amd-k10-5-core-cache-unlocking-guide
As far as cooling, it becomes a 125W CPU like the Phenom II 955 so it will need more cooling. Usually the TCTL calculation becomes FUBAR'd when unlocked, so just monitor socket temperature.