If Afterburner will allow it, then technically you can. It would not be advised to attempt such a feat...
I found out how to do it here https://www.youtube.com/watch?v=s42qs8SxiiA Now I can run fifa 15 almost smooth but allot better than the laggy game that was before the OC. Temperatures seemed fine and no freezes or crashes.
As long as you do not up the voltage you should be ok. I have an asus n75 with some Nvidia card and can overclock within the temp specs. Both cpu and gpu are ok when I overclock.