Mine silver iMac 24 with 16GB RAM arrived last night (Saturday). Just finished setting up. Somehow whenever reboot, it will appear to be booting very slow after keying in password and then reboot again. Had to try a few times before I could get it to boot. Seems that if I wait for a minute or two before logging in, the success rate is higher. Also the recognition of the magic mouse seems slow. But once I touch the Touch ID button, the mouse is recognised.