Upgrading graphic card to GTX 765m?

Hello! My question is if I can upgrade the video card of my iMac Intel 21.5" mid-2010 (EMC 2389, i5-680 3.6 GHz, 8 GB RAM) to, for example, a GeForce GTX 765m or any other, since I saw a couple of videos but talking about the 27” model.

The problem is that the video card blew, I guess. The iMac started running very slow suddenly, and after a couple of days it stopped turning on (after a few seconds while turning on, it suddenly turns off).

So in case to change the video card, which ones would the motherboard support or which cards would you recommend me for the change?

Thank you!