Have you checked to see if your RX 480 is still under Warranty from the card Manufacturer?
If it is, I would open an RMA Request from the card's Manufacturer Support to either replace or repair your GPU card.
If it isn't under Warranty, See how much the Card's manufacturer support will charge you for repairing your card. You can try and see if a AMD Service Center is near by that you can send the card in for repairs and find out how much it will cost if the card's manufacturer can't repair it.
You can open a AMD WARRANTY REQUEST and see if they can tell you where is the closest AMD Service Center is: AMD Warranty Request Form | AMD .
NOTE: The Warranty on the GPU card is valid, if still applicable, from AMD if purchased from AMD.com.