Apple Computer iMac 27-inch 3.5 GHz Core i5 (i5-4690) iMac 27-inch 4.0 GHz Core i7 (i7-4790K) Compatible Order Number MF886LL/A Compatible Model Number
iMac 21.5" A1418 Late 2015 Logic Board 2.8 GHz Core i5 16GB Ram || NO - Part Haven
iMac 27" Logic Board, 3.3GHz, i5, 2GB VRAM, Late 2014 / Mid 2015 DIY Parts replacement Logic Boards
Probably of no use to anyone here, but the 2.8GHz late 2015 iMac logic board requires a different heatsink than the 1.6GHz board because the CPU is in a different location. Ask