iFixit

Connect the small plug on the SATA power cable to the socket labeled SSD Power on the logic board.

The socket is located just below the GPU heat sink.

Next, locate the 90º connector on one end of the SATA data cable.

The color of your SATA data cable may be different than the cable shown here.

Connect the 90º end of the SATA data cable to its socket on the logic board next to the SATA power connector.

With both SATA cables connected, they should look like the logic board shown in the photo.

Next, while holding the new hard drive cables against the GPU heat sink, lower the bottom edge of the logic board back down into the outer case.

When re-seating the logic board, it is helpful to tape the many connectors that attach to it out of the way to avoid them getting trapped beneath the board.

Before pushing the logic board against the back of the outer case, first route the hard drive cables in the channel near the bundle of power cables.

As you place the logic board into its recess, route the hard drive cables through the small channel cut into the plastic pressure wall near the fins of the GPU heat sink.

In the next few steps, you'll install your new drive into the case of your EMC 2428 iMac.

The drive will sit behind the optical drive in the space highlighted in red.

To secure your new drive in your iMac, you will need to place high strength double-sided tape at the four corners on the side of the drive with the SATA connectors.

Peel the backing off one side of the double-sided tape and place the pieces at the four corners of the hard drive.

Connect both the SATA data and SATA power connectors to your new hard drive.

The SATA connectors will be nearest the top of the iMac when the hard drive is installed.