I have this issue recently and I followed the troubleshooting outlined here:
Macbook is beeping three times and won't start up.
1. tested both RAMs(individually), no problem.
2. tested both RAM slots(individually), no problem.
3. problem when putting both RAMs back.
Appreciate very much on any advise I could get.
MacBook Pro
Typically yes a RAM issue.
Try resetting the SMC http://support.apple.com/kb/ht3964
1 Choose Apple menu > Shut Down.
2 After your Mac shuts down, press Shift-Control-Option on the left side of the built-in keyboard, then press the power button at the same time. Hold these keys and the power button for 10 seconds.
3 If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.
4 Release all keys.
5 Press the power button again to turn on your Mac.
Try resetting NVRAM/PRAM http://support.apple.com/kb/ht1379
1. Shut down the computer.
2. Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 4.
3. Press and hold the Command-Option-P-R keys.
4. Turn on the computer.
5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
6. Release the keys.
SOLVED: Getting three Beeps, Not RAM error - MacBook Pro 15" Unibody Late 2011 - iFixit
Thanks so much. I did the RAM reset, and it is working now. Have a good day.
Macbook is beeping three times and won't start up.
