Only the logic board remains.
If your iMac is equipped with the Fusion Drive option, you will also need to remove the SSD from the back side of the logic board and transfer it to your new logic board. Remove the SSD by following these steps.
The logic board includes the PRAM battery. If your replacement logic board does not include the battery, you can transfer the battery over from your old logic board by following these steps.
When reassembling your iMac, remove the CPU from the heat sink and reinstall it separately from the heat sink. This will make sure it's installed correctly and prevent damage.
Follow our thermal paste application guide to reapply the thermal paste to the graphics processor (GPU). You should also replace the thermal compound or apply thermal pads to the VRAM chips.
During reassembly of the logic board, pay attention to the position of the I/O connectors. When the board is back in the case, insert a USB or Thunderbolt cable into one of the connectors to align it perfectly.
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