11-30-2014, 06:46 PM
First, try both zapping PRAM and doing a SMC reset.
Zap PRAM: Using a wired USB keyboard, hold down Command+Option+P+R on startup and continue to hold down those keys until you've heard at least 3 boot-chimes.
SMC Reset: Shut down and unplug the iMac. Leave it unplugged for at least 15 seconds. Then plug it back in and boot.
When you've booted after this, go into System Preferences > Displays and hold down the option key to see the "Detect Displays" button. Click the Detect Displays button.
...
If this doesn't fix it then download SMART Utility and when you run it, use the "Install SAT SMART driver" option under the "Smart Utility" menu and install the SAT drivers. Reboot. Then run the SMART Utility again.
The SAT drivers may permit your computer to display SMART status of external drives like your SSD. Do all drives pass SMART tests?
Zap PRAM: Using a wired USB keyboard, hold down Command+Option+P+R on startup and continue to hold down those keys until you've heard at least 3 boot-chimes.
SMC Reset: Shut down and unplug the iMac. Leave it unplugged for at least 15 seconds. Then plug it back in and boot.
When you've booted after this, go into System Preferences > Displays and hold down the option key to see the "Detect Displays" button. Click the Detect Displays button.
...
If this doesn't fix it then download SMART Utility and when you run it, use the "Install SAT SMART driver" option under the "Smart Utility" menu and install the SAT drivers. Reboot. Then run the SMART Utility again.
The SAT drivers may permit your computer to display SMART status of external drives like your SSD. Do all drives pass SMART tests?