How about other components? There are two coolers one deicated to cpu but other cools chipset, power circuits, etc. Also memory and other stuff being cooled by throwing fresh air from the bottom to the top. Now whole case being cooled by lonely video...
80C is a temperature limit for 970. It will throttle down until temps are lowered.Try installing MSI Afterburner software and switch fan speed to auto or some custom profile. You will get better perfomance because 970 wouldn't throttle anymore.