Our friends over at ClassicPlatforms were kind enough to post this excellent guide for volt modding a Gigabyte GA-MA790x-UD4P so I figure's I'd post a link to it here.
Macsbeach98's Gigabyte GA-MA790X-UD4P Vcore Voltmod
Macsbeach98's Gigabyte GA-MA790X-UD4P Vcore Voltmod