Released June 2012 / Core i7 processor with Turbo Boost / Up to 1 GB DDR5 Video RAM

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Dual Drive selection and compatibility

Hello, I'm thinking of upgrading my MacBook Pro with a second drive. I am not sure which i should use and which is the best option compatibility wise.

My options are:

  1. SSD 850 EVO 500GB Samsung 2.5" Sata III MZ-75E500B/EU
  2. SSD MX300 525GB 2.5" SATA3 Crucial CT525MX300SSD1

I am also wondering whether I should place the new drive where my MacBook's initial HD is positioned and put my current HD in the optical drive bay.

And a last question:

Since I am running Bootcamp on my MacBook as well, should I install both macOS and Windows on the SSD and just keep the current HD for data storing space?

Thanks in advance, Andreas

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2 Answers

Chosen Solution

You might encounter two different issues here.

The first is some MacBook Pro's have a SATA II (3.0 Gb/s) optical drive port. Here's a good reference: OWC Data Doubler it makes no difference who's carrier you have as the issue is within the Mac's logic board. If you have one of the odd systems you'll need to find a older fixed speed SATA II (3.0 Gb/s) drive for the optical bay.

The second issue you can face is the Apple HD does not have crash guard onboard so moving it over to the optical bay does put it at risk if you bounce the system while the drive is running. Only the HD bay has crash guard protection. So I would leave the HD in its current position and put the SSD in the optical drive bay.

Frankly, if you have one of the odd systems you might as well just forget the dual drive config and just get a Seagate FireCuda SSHD replacing your current HD.

Update (07/27/2017)

Here's some info on SSHD's: SSDs vs. hard drives vs. hybrids: Which storage tech is right for you?

Here's info on the Seagate FireCuda 2.5" SSHD. Just keep in mind this is a fixed SATA III (6.0 Gb/s) drive.

As for which SSD you had listed:

  • I've used the Samsung 850 EVO in quite a few systems and I do find they are tops in both quality & performance!
  • The Crucial SSD is also quite good from a performance perspective. I do find their documentation & support is a bit thin.

Frankly I don't have an issue with either. So its more likely an issue of cost and availability.

One point I wouldn't leave the optical drive bay empty. At least get the optical drive carrier so the slot is covered and the stiffness of the system can be maintained. This is important if you grasp the system with one hand where the optical drive would be.

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hello @danj ! help much appreciated. Just a question, how can I define whether i have an odd system?


First you'll need to check your system here: EveryMac - Lookup plug in your S/N will get you your exact systems specs and the Series Identification string i.e. MacBookPro9,3 which you can then locate in the notes section in the OWC Data Doubler link I posted. Once you know if your system is clean or not let us know.


Already checked my system @danj . Got a model ID MacBookPro9,1, which as I understand is on the odd side, right?


Sadly, that could be the case ;-{

The rub here is the CPU's clocking I was never able to validate which ones had problems and which worked reliably (just to many versions). The Mid 2012 2.6GHz model appears to be OK, yet the 2.7GHz model fails.

We gave up trying, and instead went with the Seagate SSHD as the HD replacement or now we are jumping to SSD's instead and leave the optical drive.


My model is the Mid 2012 2.6GHz actually. The only reason i said about Samsung/crucial apart of being SSD is just because are the easier for me to find in my place, since I need the hard drive immediately - plus am not used to SSHD(i don't know pros and cons). But if there is even a chance having a problem with those i guess I should wait and go with your solution.

PS. i have already removed my optical drive a couple of months ago since it was not working, and since there is that space open i am trying to get use of it


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1. Have not tested anything so I assume both SSDs would work perfectly fine,

2. I would assume the original space in the MacBook is the best so I would place the SSD there and the old where the optical drive is.

3. Yes. I would partition the SSD and install boot camp there and use the old hard drive as a dedicated storage device,

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Thanks for you reply @trulszk . It would be great if anyone has an idea on the first question. Whether i should choose Samsung or Crucial hard disk.


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Andreas Iosif will be eternally grateful.
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