I've just gotten a new iMac 27" 5k (Late 2015). Works great, apart from one minor, yet annoying issue. Whenever I reboot, it seems bot my mouse and keyboard are not working once presented with the login screen.

I can sort of solve this doing the following:

  1. When at the login screen, I plugin the usb cable in my keyboard and it (and only it - not the mouse) gets responsive. From there, I can either login and reboot or reboot directly.

  2. Once the machine has rebooted and the "boot up sound" has played, I remove the cable.

  3. When at the login screen, both the mouse and keyboard are now working again.

Has anyone ever encountered this issue before? It's really cumbersome to repeat this procedure every time I do a reboot.

My system overview:

  • OS X El Capitan v. 10.11.4
  • Processor: 4GHz Intel Core i7
  • Memory: 8 GB 1867 MHz DDR3
  • AMD Radeon R9 M390 2048 MB

1 Answer 1


Reseting the NVRAM seems to solve the issue.

Here is the procedure.


  • Finally! Guess something has gone wrong during the initial setup process. Anyway, all god now. Thank you! Commented Apr 10, 2016 at 8:34

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