The pixel patcher bypasses the driver Bios signature check. With a modded Bios the signature is invalid and causes Windows not to be able to load the driver for the card (code 43). AFAIK a RX 580 with a modded Bios has never needed the pixel patcher to bypass the Bios signature check. If OverDriveNtool wasn't working it may be because the drivers changed something in the API, which has nothing to do with the pixel patcher.
The same thing happened when AMD switched from the Crimson Relive to the Adrenaline drivers, which caused the Claymore overclocking parameters to stop working until he updated the miner in v10.3 so they were compatible with the Adrenaline drivers.
https://bitcointalk.org/index.php?topic=1433925.msg27476189#msg27476189Try this if OverdriveNtool won`t work. It helps to me.