cool wolf, the maximum operating temperature for this card 100c ... keep your overclock under 90c and you should be good... do you have the gddr5 version or ddr3? ... overclocking the gddr5 reveals much better performance than compared to the ddr3 variant. because if you have the ddr3 variant , you need to overclock the core and memory for a decent performance gain, since the slow memory bottlenecks the gpu itself where as the gddr5 has a really fast memory clock to start with so increase the core clock alone will give you decent gain in fps....
i have the renamed version of this card (r7 m265 ddr3) no matter how much i overclocked the core i see no performance gain, but a soon as i overclocked the memory, i gain a hell of a lot of fps... so stock i had 825mhz on the core and 900mhz on memory .. bf4 temp revealed 63c before overclock ... got core upto 960mhz stable and 1120mhz on memory stable... temps shot upto 75c ... but that is still nowhere close to 100c.... before the overclock i managed the game on low preset for about 40fps but after the overclock i was hovering at about 45fps at medium preset... before the overclock however i had to change the thermal interface material as the one that can from the factory was shit.. i replaced it with some arctic silver 5 on both cpu and gpu .. before the thermal replacement i managed 78c in games (without OC) and after replacement i hung around 65c (without OC) so i managed to overclock and still keep temps below what it originally was. so if your going to overclock sir( regardless of the card type ) , i recommend you change the thermal paste, and make sure the your fan is not dusty and make sure there is nothing blocking the heat-sink such as dust,lint,dirt,etc ... this will ensure your laptop runs cool as possible under maximum load... it will only benefit you in the long run. and always use your laptop on a flat surface, make sure there isn't anything blocking the vents grills underneath... i bid you the best of luck sir in your pursuit to overclock your card. but remember you need to understand the dangers of overclocking and if you are new to it , do some research on what results other people got .
the key to overclocking is patience , and a clean laptop, maintenance for dust should be done every 6-12 months and thermal paste replacement should be done every 2 years... hope this paragraph helps you sir and if you have anymore question , please feel free to ask .. cheers!