Boot the MBP from the Snow Leopard disc.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 your iMac into Target Disk Mode by pressing and holding the T key as you startup.The only ways to get around this is to use another disc or do the following: It’s either one that belongs to another Mac or it’s a retail version that’s earlier than 10.6.6. My guess is that you’re not using the grey disc that shipped with your iMac. 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). And Yes, it’s trying to tell you something!Ī 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. Upon checking after Monomeeth's answer I can add that the original Snow Leopard disc I am trying to boot from is indeed a retail version containing 10.6.3. Mac OS X El Capitan 10.11.6 installed on the internal drive.The Mac boots fine otherwise (both normally and in Safe Mode), but just doesn’t want to boot from this disc and I have no idea why, but I’m pretty sure the beeps are the key! :) Specifications: I have no reason to suspect a problem with either the disc (no scratches or other signs of damage and it boots a Mid 2009 MacBook Pro just fine) or the optical drive (it loads other discs fine). To do this I am trying to boot from an original Snow Leopard disc in the SuperDrive. Is my Mac possessed? Assuming not, what is it trying to tell me? Backgroundįor various reasons I want to re-install the original Mac OS X. booted into Apple Hardware Test and no problems found after running extended tests.used a timer to verify it is definitely 3 seconds in between the 3 beeps.rebooted a number of times and the same exact pattern occurs.checked with Apple KB - About Mac startup tones and this pattern is not listed as an official form of communication.They beep as follows:īEEP BEEP BEEP BEEP BEEP BEEP and it continues until I power off. When I try to boot my Mac I get nothing but strange beeps.

Macbook pro 3 beeps power off