Trying to boot Sierra via USB - Circle with slash

So like I said, I am met by a circle with a slash through it right after the apple logo. Here is some info on it: http://imgur.com/a/K2Zct

My system: Intel(R) Core(TM) i7-4820k CPU @ 3.7 GHz Gigabyte x79-UD3 GTX 980

Any help would be much appreciated!