What is that shiny cover for?

[Lankyman]

I have often wondered when I have cracked open my iMac what the big shiny disk with the wire attached is for in my iMac. It sits under where the HDD is installed. Does anyone know - see image.

 

[SaSaSushi]

I believe your are referring the rear Apple logo.

See step #23 in this iFixit teardown.

The Apple logo is no longer just for looks, it now has a job to do. Earlier aluminum iMacs had an aluminum front and a plastic back. In contrast, this iMac features an all-aluminum enclosure, which is great for looks, but terrible for Wi-Fi. The Apple logo is the only plastic area on the back of the iMac, and Apple has integrated an AirPort antenna into that space.

 

[hfg]

I have often wondered when I have cracked open my iMac what the big shiny disk with the wire attached is for in my iMac. It sits under where the HDD is installed. Does anyone know - see image.

I think the WiFi and Bluetooth antennas are in that area.

 

[Lankyman]

Ah! so that’s what it is and if so I now understand the logic. Each time I have opened up my iMac I have pondered over what it was for. I have to confess although I have looked at the ifixit tear downs numerous times I had obviously not been paying close enough attention.

Thank you for the prompt replies.