well if you are using HIS 9550 , i remember can push it to 65% for the core clock with stock heatsink ...

with coolviva can reach its limit ... my fren burn the card due to extreme high clocking ...

i think it went over 90% overclocking in the core only ... memory clock is kinda bad ...

cant go that high not more than 30% even with a proper ramsinks and fan on it

Using atitool btw .... can play lots of game freaking smoothly on that card