Fusion drive HD portion upgrade question

[mordomordo]

Good evening

I want to upgrade my imac 21.5 2015 drive to ssd.
There's 1tb fusion drive (24gb soldiered in ssd + 1tb HDD) now and I wonder if I need to remount fusion drive after swapping it's hdd part?
I would like to keep using its pcie ssd
Theres no data I want save.

 

[Juicy Box]

Yes, you can continue using the OEM SSD all by itself.

Since the old SSD will most likely be much faster than the new SATA SSD, you could create a new Fusion Drive with the new SATA SSD. Some people don't recommend it, but there really isn't much logic to their reasoning. It will just give you a much faster and much larger drive versus using just the SATA SSD.

The above is assuming that you are replacing the HDD with a SSD and not another HDD.

One thing that is highly recommended, is defusing the current Fusion Drive prior to opening your Mac. This could prevent some weird boot issues later on.

After separating the two drives in your Fusion Drive, you can test speed of your 24GB SSD, to see if it would be worth it to Fuse it with the new SATA SSD.

 

[DeltaMac]

The OEM SSD is not soldered in place. It is in a card slot.
Challenging to replace (it's on the back side of the logic board), but it's not worth much when used by itself (only 24GB)
But, a PCIe m.2 card would potentially be faster than any SSD that you would put in the SATA drive bay.

 

[mordomordo]

Yes, you can continue using the OEM SSD all by itself.

Since the old SSD will most likely be much faster than the new SATA SSD, you could create a new Fusion Drive with the new SATA SSD. Some people don't recommend it, but there really isn't much logic to their reasoning. It will just give you a much faster and much larger drive versus using just the SATA SSD.

The above is assuming that you are replacing the HDD with a SSD and not another HDD.

One thing that is highly recommended, is defusing the current Fusion Drive prior to opening your Mac. This could prevent some weird boot issues later on.

After separating the two drives in your Fusion Drive, you can test speed of your 24GB SSD, to see if it would be worth it to Fuse it with the new SATA SSD.

Thanks for mentioning defusing fusion drive before opening. Why you think it wouldn't be worth fusing it back again?

 

[mordomordo]

The OEM SSD is not soldered in place. It is in a card slot.
Challenging to replace (it's on the back side of the logic board), but it's not worth much when used by itself (only 24GB)
But, a PCIe m.2 card would potentially be faster than any SSD that you would put in the SATA drive bay.

How can I verify if pcie slot is upgradable?

 

[Juicy Box]

Why you think it wouldn't be worth fusing it back again?

Do you mean creating a new Fusion Drive with the old and new SSDs after replacing the HDD with a new SSD?

Well, no surprise, there are pros and cons to doing it and not doing it. Some of these totally depend on the shape of your current OEM SSD.

Pros:
If the current OEM SSD is in pretty good shape and has decent read and right speeds, creating a new Fusion Drive with the OEM and SATA SSDs could boost drive performance over using the SATA SSD alone.
Even with the tiny 24GB SSD, there could be a noticeable difference with drive performance, especially with write speed.

Cons:
It requires an extra step, and adds complexity to the drive set up.
If the current OEM SSD is in bad shape and has horrible read and right speeds, creating a new Fusion Drive with the OEM and SATA SSDs could have no impact on drive performance over using the SATA SSD alone, making it pointless.

How can I verify if pcie slot is upgradable?

If you want more information about the PCIe SSD options, check out this tread:

A list of successful iMac 27" (2012-2019) SSD upgrades

Here you can find and discuss all the collected knowledge regarding upgrading the HDD, blade SSD and CPU of a 27" iMac 2012-2019, as well as a list of performed upgrades. Here is a list of all 27" iMac models subjected in this thread: Late 2012 - 13.2 - MD095LL/A (2.9Ghz i5-3470S, HDD only /...

forums.macrumors.com

It has a bunch of information on compatible drives, adapters needed, tools, potential problems and fixes, etc.

Also, you can look up iFixit for guides, tools, and adapters, SSDs, etc.

Replacing the OEM SSD with something aftermarket requires the logic board to be totally pulled, but if you are comfortable doing it, you could get a huge speed boots for not much more $$$ than using a SATA SSD.

I personally don't like using the adapters, though. Maybe people have use the adapters with no issue, but there are also people that have had issues with them. And since it isn't exactly quick or easy to make adjustments or replace the adapter, I would most likely avoid doing it.

It is better to just look at the thread I posted above to get an idea of what you would be getting into. It is a lot more complex than just replacing the HDD with a SATA SSD, and there also seems to be more issues with replacing the blade SSD than just using a SATA SSD.

But, the speed of replacing the blade might be worth it to you to try it.

 

[DeltaMac]

How can I verify if pcie slot is upgradable?

Are you asking if the card slot is not a slot (but soldered)?
It's not soldered on that iMac model. (iMac 21.5-inch, Late 2015 is either iMac16,1 or iMac16,2)

The slot can take most any NVME drive. All you need is a slot adapter. The Sintech is a good choice.
You do need to make sure the firmware is updated.
If you have been running macOS 10.13.6 High Sierra, or newer, you will fine.

 

[mordomordo]

Do you mean creating a new Fusion Drive with the old and new SSDs after replacing the HDD with a new SSD?

Well, no surprise, there are pros and cons to doing it and not doing it. Some of these totally depend on the shape of your current OEM SSD.

Pros:
If the current OEM SSD is in pretty good shape and has decent read and right speeds, creating a new Fusion Drive with the OEM and SATA SSDs could boost drive performance over using the SATA SSD alone.
Even with the tiny 24GB SSD, there could be a noticeable difference with drive performance, especially with write speed.

Cons:
It requires an extra step, and adds complexity to the drive set up.
If the current OEM SSD is in bad shape and has horrible read and right speeds, creating a new Fusion Drive with the OEM and SATA SSDs could have no impact on drive performance over using the SATA SSD alone, making it pointless.


If you want more information about the PCIe SSD options, check out this tread:

A list of successful iMac 27" (2012-2019) SSD upgrades

Here you can find and discuss all the collected knowledge regarding upgrading the HDD, blade SSD and CPU of a 27" iMac 2012-2019, as well as a list of performed upgrades. Here is a list of all 27" iMac models subjected in this thread: Late 2012 - 13.2 - MD095LL/A (2.9Ghz i5-3470S, HDD only /...

forums.macrumors.com

It has a bunch of information on compatible drives, adapters needed, tools, potential problems and fixes, etc.

Also, you can look up iFixit for guides, tools, and adapters, SSDs, etc.

Replacing the OEM SSD with something aftermarket requires the logic board to be totally pulled, but if you are comfortable doing it, you could get a huge speed boots for not much more $$$ than using a SATA SSD.

I personally don't like using the adapters, though. Maybe people have use the adapters with no issue, but there are also people that have had issues with them. And since it isn't exactly quick or easy to make adjustments or replace the adapter, I would most likely avoid doing it.

It is better to just look at the thread I posted above to get an idea of what you would be getting into. It is a lot more complex than just replacing the HDD with a SATA SSD, and there also seems to be more issues with replacing the blade SSD than just using a SATA SSD.

But, the speed of replacing the blade might be worth it to you to try it.

I saw that thread. Looks like everybody upgrades only 27" imac. I'm not sure if there's a point to spend £80 on new blade and adaptor tonupgrade £190 worth imac. If only apple would let me install there ventura...

 

[mordomordo]

Are you asking if the card slot is not a slot (but soldered)?
It's not soldered on that iMac model. (iMac 21.5-inch, Late 2015 is either iMac16,1 or iMac16,2)

The slot can take most any NVME drive. All you need is a slot adapter. The Sintech is a good choice.
You do need to make sure the firmware is updated.
If you have been running macOS 10.13.6 High Sierra, or newer, you will fine.

Mine is 16.2 and has fusion drive. So if theres a fusion - there must be pcie slot. So I assume there's my 24gb blade plugged

 

[DeltaMac]

The thread is about the 27-inch, but the 21.5-inch has the same chipset (well, same generation of chipset/CPU), so supports the same types of hardware, and the basic process to replace the PCIe is much the same. You still must completely remove the logic board to get at the PCIe slot. The differences will be the actual task (where the screws and connectors are - and what to remove, in what order), and each model is a good challenge to do the replacement.
It would be nice if you could get to the PCIe slot at the same time that you can get to the SATA hard drive, but that's just not possible. I have upgraded 3 21.5-inch iMacs from that era, replacing both hard drives and SSD cards. It's a tricky job, with lots of steps, and lots of things to watch out for. Be sure to get replacement tape strips before you start, and be careful to completely clean the tape areas, so no old adhesive, or other tape residue is left, before you re-tape.

The iMac16,2 can be either a non-retina model, or a Retina 4K. I think there is minor assembly differences, so you would want to make sure which one you have. There are different steps on the iFixit.com repair instructions between those two different iMacs.

 

[mordomordo]

The thread is about the 27-inch, but the 21.5-inch has the same chipset (well, same generation of chipset/CPU), so supports the same types of hardware, and the basic process to replace the PCIe is much the same. You still must completely remove the logic board to get at the PCIe slot. The differences will be the actual task (where the screws and connectors are - and what to remove, in what order), and each model is a good challenge to do the replacement.
It would be nice if you could get to the PCIe slot at the same time that you can get to the SATA hard drive, but that's just not possible. I have upgraded 3 21.5-inch iMacs from that era, replacing both hard drives and SSD cards. It's a tricky job, with lots of steps, and lots of things to watch out for. Be sure to get replacement tape strips before you start, and be careful to completely clean the tape areas, so no old adhesive, or other tape residue is left, before you re-tape.

The iMac16,2 can be either a non-retina model, or a Retina 4K. I think there is minor assembly differences, so you would want to make sure which one you have. There are different steps on the iFixit.com repair instructions between those two different iMacs.

Good to know that you've done a couple 21.5 imacs. In case sth goes I'll ask you for advice.
There's plenty of tutorials online. I found owc yt vidoes more helpful then ifixit. I've got all the tools and hope. My plan is;
-swap genuine apple ssd blade with new wd sn770 512gb(it's more then enough) + adaptor
-remove internal hdd and leaving sata socket epmpty
-having already ordered crucial mx500 as external drive for backups or any excess data
Should I know anything else?

Edit: lot if users complains for wake from sleep problem. Do you know how devices you upgraded performing?

What adaptor you recommend? Looks like sintech doesn't like wd blades