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macrumors 6502a
Original poster
Aug 13, 2011
Anyone with any experience of upgrading/replacing the internal SSD with something like the Transcend JetDrive 855?

I have checked and this seems to be compatible with my 15" MBP L,4 (mid-2015) with an APPLE SSD SM0256G that I wish to swap out.

I've read a review
and watched the videos
from Transcend,
& from a third party,

That second video made a number of recommendations which I set out as an exhaustive list. Some steps seemed neat:
a) using 10.4 Mojave (which I have)
b) plug the 855 unit (with the 850 SSD inside) into the Thunderbolt drive (which I have)
c) and use disk utility to format the 850 SSD as APFS

** I discovered that APFS was not an option and that it is necessary to select

Show All Devices

and not just the Volume

in order to select Mac OS Extended (Journaled) and


d) download & install SuperDuper ['spose that ought to be done beforehand]
e) open SuperDuper and copy all the contents from the Apple SSD over onto the Transcend 850 SSD
[that apparently took 22 minutes elapsed]
then a neat trick
f) go to System Preferences to switch the Start-up Disk from the native Apple SSD to the Transcend 850 SSD that is connected via Thunderbolt
g) Restart & prove to yourself that the Transcend 850 SSD is working including check on disk utility
h) then power down and set about the task of unscrewing the back, unplug the battery, swap out the Apple SSD & replace with the Transcend 850 SSD (having removed it from the 855 housing)
i) plug back the battery
j) put on the back, flip over and power up to prove to yourself that the Transcend 850 SSD is fitted and now working
k) power down, flip over and put all screws back in
l) flip over, power up [takes a little longer first time] and be reassured that Transcend 850 SSD is indeed now in charge
m) now fit the Apple SSD into the 855 housing and plug that into the Thunderbolt drive for use as Time Capsule or some other storage purpose.

Seems straightforward but I'd welcome reassurance that others have tried this route with success.

I have just over a year of AppleCare+ to run and appreciate that it might be wise to swap back the SSD before raising any issue with Apple ...
Last edited:


macrumors 6502a
Original poster
Aug 13, 2011
Well, I've done the deed. I learnt two things:

1. Need to format as GUID, which is only done by first selecting All Devices
2. Battery was difficult to unplug, so I just did the swap without out doing that


macrumors newbie
Mar 7, 2020
Hey StrollerEd,
im curious to hear how your getting on with the Jet Drive SSD now that its been some time? im looking to upgrade my mid 2014 256gb drive to something larger. Im also considering trying an NVMe SSD since they're cheaper and faster but they can also have associated issues like (sometimes) significantly worse batter life/charge, i will have to disable hibernate and some people have had high temperature issues since upgrading to Catalina.

Have you had any issues or does it just function exactly the same as an original apple ssd?

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