This logic board does not come with the CPU, to use this board you need to pull the CPU from your old board and move it to this one.
This item will work in the models listed below:
iMac (Retina 5K, 27-inch, 2017)
Model No: A1419
Model Identifier: iMac18,3
Apple Order No: MNE92LL/A (3.4 GHz), MNEA2LL/A (3.5 GHZ), MNED2LL/A (3.8 GHz)