Changing GPU : selling my amd rx 5600 xt and putting back an old gt 610. What should I do ? Big sur

I have a "hdmi no signal" after verbose mode, with no error apparently. I just switched the gpus, without doing anything in the config.plist file.

Am I missing something. Apparently, gt 610 is compatible with big sur. Do you guys have any idea how to solve this ?

Thanks