Bonne année! Happy New Year!
Does your motherboard provide the VGA/DVI/DVI port(s)? If so, would you please connect your monitor to one of them? And enable the external PCI-E port in the BIOS/SETUP/UEFI. If not, I think you'd better provide the information about your motherboard, such as its model number and vendor name. I am glad to check it whether it supports your graphics card, and provide further suggestions. Good luck!