2011 iMac gpu upgrade

[UssCompany]

Hi
I own a Mid-2011 21,5 iMac, and I was thinking about upgrading the gpu. It's currently running AMD Radeon HD 6770M 512 MB. (The only modification I've made to my Mac was upgrading RAM to 16) I was planning to buy the upcoming R9 M390X. Will this work?

 

[mhafeez]

I think you'd be better choose the right GPU by referring to the previous successors. All the best.