u can strat by tellin which batch ya 550BE is... aint no voltage adjustment needed, as long as u load d correct bios + set acc, d cores will be unlocked IF d chip comes w/ healthy locked cores. 

as long as there's a down core option in bios (which i'm sure all boards which can do core unlockin have) will do. 
force 3 core in down core option will do bro, asus is more advance coz their bios let users to chose which core to disable. eg if 3 cores there're options of:

1> Core 0, 1 & 2
2> Core 0, 1 & 3
3> Core 1, 2 & 3

i mite be wrong thou, but d logic is something similar i guess... 

as long as there's a down core option in bios (which i'm sure all boards which can do core unlockin have) will do. 

what is d symptom after acc or whatever core unlockin feature called by msi enabled? 

if that's d case most likely d locked cores are crippled. 

fsb to be replaced by htt. 

cpu-specification as in d one shown in bios, not ya pc specification. 

play the multiplier..
take the playar, and pull out the capasitor