The 7750 Can take upto 95 - 100 C. If you take it above 105 etc. it will probably fire up
And using your card continously on those temps will melt it for sure.
So even if you do overclock the GPU or whatever, never let the temp. go above 80 - 82 C during full load.
Thats the optimal safe zone i guess.
I use an ATI 6750 and i never let the temp. get above 65C, to be safe and to make sure it lasts as long as possible