Tilt the top of the logic board away from the rear enclosure.

Lift the logic board straight up and out of the iMac.

Be careful not to snag the board on any of the rear case's screw posts.

The I/O boards at the bottom of the logic board will be the greatest challenge. It is recommended to pull gently to avoid any damage.

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.