I'd like to oc it for a better performance in game. I've read a little to be sure i wasn't wrong about OC and correct me if I'm wrong but it can actually increase the performance ingame right ? well that would be my reason and the temperature while being used goes to max 70-75.
You can try it, but it wouldn't make that big of a difference i think. Seeing the oc'd version from xfx only does 50mhz more seems to be indicating it's not a great overclocker but i don't know the 4890 myself so i am not sure.