Amazon.com: Valley Of The Sun Original 2GB Graphics Video Card GPU Replacement, for Dell Alienware Gaming Laptop M15X M17X R2 R4 R5 M18X R1 R2, NVIDIA GeForce GTX 860M GDDR5, MXM VGA
Flashed Clevo GTX 860M works fine in 27 iMac mid 2011 only on external screen | MacRumors Forums