GPU Clocks Too High?

Hey guys, I recently bought a used Gigabyte GTX 770 2GB. It all works well. However, when teh card is idling, it sits at 1136 mhz. And I added a 100MHZ bump to overclock it and now when under full load it gets up past 1300mhz. I have not adjusted the voltage at all. Are these clocks genuine or is MSI afterburner glitching? Thanks
 
Solution
Under load GPU adding boost clock + your OC you can pass 1300 if GPU is stable at this setting do not worry :)
And if you not trust MSI afterburner try also GPU-Z for checking clocks :)
link: https://www.techpowerup.com/gpuz/