I’m currently using the 27-inch 5k retina late 2015 iMac.
My iMac doesn’t always start up as expected. There will be a startup chime, however the screen will just remain black all the way. Sometimes it takes more 5 mins to magically start up after freezing at the black screen. And when I managed to log in, my mouse (USB) might freeze on some occasions. I have downloaded Smoothmouse to kill the mouse acceleration.
I have tried resetting the SMC and NVRAM, however it does not seem to solve the issue. I have been facing this exact same problem after exchanging 3 sets of iMac.
Was wondering if a faulty mouse could be the cause of this problem? Or could it be the Smoothmouse. Nevertheless, I still don’t think an iMac could be so vulnerable.
Any help would be greatly appreciated! Thanks!