If the card is under warranty then RMA it for repair/replacement.
If you've tried different drivers (non-Beta ones) and made sure you completely uninstalled the old drivers then it is indeed a hardware fault.
To completely uninstall old drivers goto Control Panel > System > Device Manager > Display Adapters > Right-Click your GPU and select 'Properties' > click the Drivers Tab > Click 'Uninstall'[/] then goto Add/Remove Programs and ensure your drivers aren't listed there - if they are, uninstall them.