As long as your cpu doesn't go above 80c on full load you should be fine.
The cores should average between 22C to 33C for all 4 cores when idle and a range of 61C to 69C for all cores under load you may find one or two cores are higher than the rest 5c to 10c difference that's probably because turbo mode is enabled if not and you are manually OC'ing the cpu (which disables turbo mode) all cpu's should have 2-3c difference max with turbo mode disabled
If it is and there is a 5 to 10 degree difference between the cores then you may need to re apply the thermal paste you could have an air bubble or something
If that temp bothers you you should look into an aftermarket cooler and some decent thermal paste (mx-2 or something like) which should knock a few degrees off the temperatures
The Sapphire HD 7850 2GB
The oc version is on average:
Idle around 33c
Full load a steady temperature of ~60c your temps are about right if it's not overclocked
both your cpu and gpu can be over clocked but i wouldn't recommend overclocking your cpu on a stock cooler
for overclocking your Gpu theres:https://www.sapphireselectclub.com/ssc/TriXX/TriXX.aspx
for your cpu:
Theres a few guides and videos to watch.
Hope that helps you