That's fine... I am not sure of the exact thresholds for a 4650, but I know you have room. I believe ATI/AMD cards are usually good past 80. I run my ol' 295GTX up to 80 without issue. GPU's always have higher temp limits than CPU's, so don't be afraid of 52. May want to try a program to see full load temps just to be sure, such as RivaTuner, and possibly manually run the fans higher if you are worried.