iMac graphics card upgrade
I have a 27 inch iMac mid 2010, running High Sierra. I’d love to upgrade to be able to use a more recent OS, but I need to change the ATI Radeon graphics card. Is there anyone who can advise me which would be the best upgrade? I love my iMac and I’d rather upgrade than try and sell it(not give it away).
iMac 27″, macOS 10.13