This seems to be an issue with the motherboard, please consider replacing it. You can contact the Out of Warranty department 1-800-288-4410 (U.S.Customer only). In case you’re from different region please let us know.
Thanks and regards, Senthil S #iworkfordell. To know more about Dell Product Support, Drivers & Downloads, Order & Dispatch status -> choose your region US / India . For Dell support videos clickhere.