I've just installed Kali as the only OS on a 2009 (late) iMac. The issue is during the startup process, four screens show up on my monitor (one up right, one up left, one bottom right, one bottom left). They are all identical and I can still login to my user account, just that they are mirroring the same image and the resolution is extremely low, so low in fact that they are unreadable to try any attempt to diagnose or remedy this condition. This problem only occurs after the boot loader screen, and before the user login. The boot loader screen displays correctly.
