Just to be clear.
Gaming is ok on a mac with BootCamp and with better drivers.
And for the graphics card, it´s very good! Why? Because it´s the best performance you can get out of 35W. I don´t think there is any other graphic cards that work that well on only 35W like 460, 560 and 560X.
You can´t compare with for example GTX 1060 that is 75W, it will never appear and work well in a thin laptop as a mac with that build quality.
I think Apple never will go back to Nvidia after the mess with all the the faulty grapghic cards from them on the 2011-2013 macbooks .
That is sad, because it would be amazing to get Nvidia on the iMacs, I have mine from 2012 left with GTX680MX. 1080 in the iMac would be a direct buy!
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If you want to play games well, build a workstation, with a good gaming screen, and buy a Razer Core X and a stand for your mac, the processor in these new ones will work perfectly with the core X
DON´T buy the 699 dollar blackmagic one from apple, you CAN´T change the graphic-card in that one.
You can use Nvidia in the Core X, but it´s easiest to use AMD.