If it's still on warranty, return it, try for a RX580 to replace it. My ASUS RX580 doesn't seem to have this problem.
Before flashing your vBIOS, I highly recommend that your contact Asus Support for two reasons:
1) See if by flashing your vBIOS your warranty is voided (if Applicable)
2) See if flashing you vBIOS it might cause the customized GPU card to malfunction due to the fact the original vBIOS was made due to specific changes in the manufacturing of the GPU card.