I'm about to upgrade my MBP mid 2012 with two SSD drives instead of the stock HDD and optical disc drive. I read on different forums that the optical drive link with the motherboard is only SATA 2 and that this will eventually cause problems with a SATA 3 SSD.

I, however, see lots of videos and articles where the optical disc drive is substituted for an SSD. Are those new SSDs SATA 2 or is this not an actual issue (with the bandwidth)?

Can I use a SATA 3 SSD instead of the optical drive? Can I "switch down" a SATA 3 drive to SATA 2? Or do I need to find a SATA 2 SSD to use in the optical drive?


I specifically want to instal two Samsung EVO 850 500 GB in my old MBP.

  • 1
    Not an exact science [hence not an answer] but every machine in the house has an SATAIII SSD on an SATAII interface. No probs in over 2 years.
    – Tetsujin
    Apr 8, 2017 at 10:33
  • @Tetsujin Good news, and are there oldish MBPs among them (mid 2012 like mine)?)
    – Mats
    Apr 8, 2017 at 10:54
  • no laptops at all, actually. 2 Mac Pros, an 08 & a 10, the others are fairly generic PCs.
    – Tetsujin
    Apr 8, 2017 at 11:00

1 Answer 1


SATA interfaces are backward compatible so you can use a SATA III drive on a SATA II/I port.

From the SanDisk Knowledgebase:

SATA II specifications provide backward compatibility to function on SATA I ports. SATA III specifications provide backward compatibility to function on SATA I and SATA II ports. However, the maximum speed of the drive will be slower due to the lower speed limitations of the port.

I have actually done the upgrade you are describing (though with one SSD and a spinning drive in the optical bay). There are no issues with SATA compatibility.

  • Actually, many SATA3 SSD have troubles with SATA1 devices. You need to check if the SSD is compatible or not. Apr 8, 2017 at 16:49
  • @Allan Thanks Allan. Your sollution is actually the one that is suggested in articles where they warn about the SATA port for the optical bay not having enough capacity for a SSD SATA III. Did you ever try putting the SSD in the optical bay? In the OCW Installation Video: The 2012 MacBook Pro's optical bay can not reliably support 6Gb/s SSDs and hard drives. It continues However, SATA 3Gb/s SSDs and hard drives will work without issues in the optical bay. The HDD comming with the MBP it is said to be a SATA 3Gb/s.
    – Mats
    Apr 8, 2017 at 18:40
  • @IsmaelMiguel - than those drives are not following SATA spec. If it complies with the spec, then it's compatible.
    – Allan
    Apr 8, 2017 at 23:00
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    @Mats - I actually put a 1TB SATA III drive (Western Digital) into the optical bay.
    – Allan
    Apr 8, 2017 at 23:01
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    @Allan My experience was with a Kingston V300 128GB. And yes, the SSD was fine and the motherboard supported that size of disk. In fact, I've installed a 1TB HDD in it and is working. Apr 8, 2017 at 23:06

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