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I purchased 2x 4GB PC3-L 12800s DDR3 1600MHz and installed both sticks, got 3 beeps when trying to boot. I removed 1 new stick and installed old 1GB stick and Mac booted up just fine. I then found out that these were the wrong RAM for my mac and so I removed the new RAM and bought and installed 2x 4GB PC3-8500 DDR3 1066MHz and got the 3 beeps again. I removed one and installed the old 1GB stick, and got the 3 beeps again. I tried every combination using the new and old or the new only and still getting the 3 beeps. Help please!!
Exactly which machine do you have? Please go here and input your serial number from the back of your machine in very fine print: https://everymac.com/ultimate-mac-lookup… UPDATE Thanks for giving us your exact machine. Install the original RAM. Zap the PRAM Here’s how to reset your PRAM: Shut down your machine. Yes, all the way down, not sleep or logging out.Press the power button and then press command-option-p-r. …Hold those keys down until your Mac reboots again and you here the startup chime.Let go of the keys and let your Mac reboot normally.If this works, install one of the new chips and boot, then do the next one.
The “data corruption” 3 beep pattern during the power-on self-test means that you (most likely) still have the wrong (or static-electricity damaged!) RAM. Go to crucial.com and find out what the right RAM is.
