Updates to the BIOS should be on the manufacturer's site. Getting the BIOS from there will also help with compatibility with your board.
Maybe it is a driver issue. Or maybe it's both -- maybe the Windows drivers have a workaround for BIOS bugs. I really don't know, I'm just trying to narrow things down.
If you don't want to try to flash your card, that's fine. I wouldn't want to either, if mine didn't have the backup BIOS on it for just in case something goes wrong in the flashing process (it's an MSI card). So I really don't blame you.
Waiting works too...