5k iMac 2015 late cpu replacement test
I have an imac 27" 2015 late model. I'm going to experiment with upgrading to Kaby lake 7700k cpu. I will share the results soon. Good luck to me.
Model A1419 / EMC 2806 / Late 2014 or Mid 2015. 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (ID iMac15,1); EMC 2834 late 2015 / 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (iMac17,1) All with Retina 5K displays
While these chips are very similar (review the specs sheets below) I don't think it will work as the systems EFI likely won't recognize the chips Device ID code.
If it does work you'll need to run some benchmarks to see if you gained any real performance.