My Mac repeatedly beeps three times on startup. What does this mean?

The leading cause of firmware issues is a power failure or problems during the macOS updates. A series of 3 beeps at a startup means your MacBook is signaling that the operating system you’re about to boot into is incompatible or that it can’t recognize some hardware on your Mac.

How to Change RAM on a Apple iMac and the three beeps hardware problem

MacBook Beeping 3 Times: What Does It Mean & How to Fix It

Resetting NVRAM/PRAM is to reset your RAM. You need to shut down your Mac and wait for a moment. Then, press the power button to start up your Mac and immediately press the Option – Command – R – R keys. Release the keys when hearing the second startup sound from your Mac or seeing the Apple logo showing up and disappearing twice.

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No, your Mac is not possessed. And Yes, it’s trying to tell you something!

A looping three beeps in between three seconds during startup is your iMac’s way of telling you that the operating system you’re trying to boot into is incompatible with your Mac hardware.

In other words, the Snow Leopard disc you’re trying to boot from contains a version of Snow Leopard that is earlier than version 10.6.6 (the earliest your iMac can support).

My guess is that you’re not using the grey disc that shipped with your iMac. It’s either one that belongs to another Mac or it’s a retail version that’s earlier than 10.6.6.

The only ways to get around this is to use another disc or do the following:

  • Boot your iMac into Target Disk Mode by pressing and holding the T key as you startup
  • Connect it to your Mid 2009 MBP with a FireWire cable (once connected it’ll be seen by the MBP as an external hard drive)
  • Boot the MBP from the Snow Leopard disc
  • Now install Snow Leopard onto the external drive (i.e. the iMac’s drive)
  • Reboot the MBP from the iMac drive and then upgrade Snow Leopard to the latest version (i.e. 10.6.8) so that you know for sure it’ll boot the iMac fine
  • Shutdown both the MBP and iMac and then try rebooting the iMac as normal from its internal drive that now has Snow Leopard installed.
  • WARNING: You should always ensure you have a backup of your data, especially when performing operations such as this!

    I too got this. I too have a mac air 2014… ram is soldered… okay so im not buying a new logic board but i did fix this. i disconnected the battery, the fan, the nve drive and the logic board from the power along with all the little snap in cables and such apple likes to include along the way, the display.. but i didnt actually unscrew the logic board i just took all the stuff off, then i cycled my power… with everything disconnected… connected everything back in order but before connecting the battery i plugged magsafe in and cycled power. ta-da. looks like basic electronics knowledge is the same for pc and mac and anything with ram. cycle out the power before you say components are fried, works like a charm even on desktop ram. plus im not going to re solder or rebuy anything i dont have to. this was after updating to big sur, sceen flickered and boom black screen in middle of update.

    dont give up whats the worst that could happen you lose some screws.

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