Pull the SATA data cable connector away from its socket on the logic board.
The SATA connector on most iMacs tends to stick in its socket on the logic board. If you are having trouble disconnecting the SATA cable, insert a metal spudger or any other thin tool into the gap between the SATA connector and its socket and twist the spudger's shaft to safely separate the two pieces.
Lift the left and right speakers out of the rear case.
The speaker cables are still attached to the logic board.
The right speaker cable may be routed under the power button cable or the CPU fan cable (or both). If so, disconnect both cables by pulling their connectors away from the face of the logic board.
Squeeze the two optical drive bracket ears together while pulling the drive up toward yourself.
It may be helpful to hold the logic board down near the optical drive connector when pulling the drive toward yourself to avoid both components lifting together.
Pull the optical drive away from the side of the rear case and remove it from the iMac.
If your optical drive is particularly stubborn to remove, try the method used in the optical drive guide from the A1144 G5 iMac.
Press the hard drive bracket down to free it from the rear case, then rotate the top of the drive toward yourself.
Pressing the top of the hard drive bracket down to release it from the rear case requires a substantial amount of force, so we recommend laying your iMac stand-side down on a table to avoid knocking it over.
Unplug the power supply cable bundle from the logic board by simultaneously depressing the locking mechanism (toward yourself) with a spudger and pulling the connector away from its socket.
Be sure to touch the chassis before proceeding to discharge any static.
Grab the logic board from its left edge and rotate it out from the rear case, using your other hand to press the RAM arms in enough to clear the rear case.
Be mindful of the ports attached to the rear of the logic board as they may stick to the rear case.
Pull the logic board straight out of the rear case, minding any cables that may get caught.
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.
