Early 2011 model, A1278 / 2.3 GHz i5 or 2.7 GHz i7 processor.

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Why can my SSD boot into High Sierra

I have an early-2011 MacBook Pro 13" (A1278). I upgraded the RAM to 8GB and installed a 256GB Samsung SSD 850 Pro. I followed the instructions How can I install OS X on a new ssd and after I installed the SSD into the laptop I got the dreaded "question mark".

I then tried other methods of getting the SSD to work when installed in the laptop such as creating a bootable USB thumb drive to install OS X but each time I installed the correctly working SSD into the laptop I got the question mark. I've gone through the MacOSRecovery and see the drive in Disk Utilities and format it correctly, reinstall the OS via the external USB device yet when I go to install the SSD in the laptop the question mark keeps appearing.

I even cloned the existing OS X onto the SSD and booted to the SSD when it was connected to the external USB device and it worked fine then. Again when I installed the SSD into the laptop the question mark appears.

I'm beginning to suspect the SATA cable but it "looks OK". Who knows. I'm about at my wits end with this issued. I spent all day yesterday trying every solution I can find on the internet but to no avail. I'm hoping someone can help with this issue. I know the SSD can't be bad since it installs OS X while connected to the external USB device. I'm almost to the point of returning the SSD and just keeping the HDD that the laptop currently has.

Any help will be appreciated.

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The hard drive/IR cable can get damaged in two ways on this model. First from the bottom case impacting it right where it comes over the final step onto the optical drive and by the rough texture on the surface of the case where the hard drive sits on top of it. I replace this cable with the more substantial 2012 cable. I also put electrical tape on the case surface and pads on either side of the cable as it comes over that last step.

MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable

BTW make sure that drive is getting formatted GUID Mac OS X Extended Journaled.

MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable Image


MacBook Pro 13" Unibody (Mid 2012) Hard Drive Cable


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Thanks for the information and link. Guess it's worth a shot to replace the SATA cable. I can't believe the SSD is defective since OS X High Sierra installed on it via the external USB cable. I'll post back once I try a new cable.


You can install a Mac system on an external drive formatted in any way, but it will not see it internally, so make sure it is GUID.


Yes..it was formatted for GUID and Mac OS Extended (Journaled).


One other quick question. When you mention "...pads on either side of the cable as it comes over that last step." what exactly are you using as "pads"?


Now you are asking for trade secrets ;-) 3M Extreme Mounting Tape



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John will be eternally grateful.
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