Solved Replace my entire PC - still black screening.

[KeplerLabs]

Can't you work with the importer/distributer of your GPU in France?

If everything fails and you are stuck with it, you should ask the community for a custom BIOS (first ask Gainward directly) which downclock it to your liking.

Maybe one of the below
www.overclock.net
Video Bios Collection | techPowerUp

Thanks !