iMac suddenly unusably slow

[Juicy Box]

I've ordered a iFixIt kit with a 2TB SSD, we see how that goes.

That is good that you are doing the internal swap. It really isn't that big of a deal, but it can be intimidating to some, so that is why so many of us on the forum recommend doing external SSDs for these iMacs.

Here are a few suggestions for the swap that you probably will not find in most guides:

1. Test the SSD prior to opening your iMac. You can connect to your Mac using a USB enclosure, or what I like to use is USB/SATA adapters, as they are quick and cheap. I suggest formatting and installing the OS externally, and also booting to make sure the drive works prior to installing.

2. Defuse or split the existing Fusion Drive (if you still can). Not doing this prior to install could cause boot problems.

3. After the install, but prior to adding new adhesive strips, consider temporarily putting the display back in place using painter's tape, and boot to make sure everything is working well. This beats adding new adhesives strips, getting everything glued up, just to find out that the SATA cables are not properly seated and your drive won't mount.

4. Consider a new Fusion Drive with your new SATA SSD and the OEM SSD from your old Fusion Drive. Once everything is working on your new drive, if you want to increase the speed, you can make your own Fusion Drive using Apple's SSD and the one you added. Apple's SSD is really fast in your model iMac, and the SATA SSD is a lot faster than your HDD, but doesn't compare to the OEM SSD. Fusing them together gives you the best the both world, a large capacity that is still super fast.

A lot of people do not like the last one, as they get scared for some reason like it might fail, but if your OEM SSD is in good shape, no reason to be scare. The huge majority of Fusion Drives fail because of the HDD, not the SSD, so no reason to be scare if you have a two SSD Fusion Drive.


Anyways, good luck on the SSD install!

 

[jbmillard]

If you don't mind losing a bit of space, i would say that the easiest is to reinstall the SO only on the SSD (and forget the HDs) and just add external capacity for additional storage. It will be also the cheapest I guess, even is not ideal.

Again, I don't want external storage because I'd either have to run it on USB 2.0 or lose an external monitor which I don't want to do.

 

[jbmillard]

You need to be very careful. It’s very easy to crack the screen when you’re putting it back together. Watch as many videos as you can before you do anything.

I have. Thanks.

 

[jbmillard]

That is good that you are doing the internal swap. It really isn't that big of a deal, but it can be intimidating to some, so that is why so many of us on the forum recommend doing external SSDs for these iMacs.

Here are a few suggestions for the swap that you probably will not find in most guides:

1. Test the SSD prior to opening your iMac. You can connect to your Mac using a USB enclosure, or what I like to use is USB/SATA adapters, as they are quick and cheap. I suggest formatting and installing the OS externally, and also booting to make sure the drive works prior to installing.

2. Defuse or split the existing Fusion Drive (if you still can). Not doing this prior to install could cause boot problems.

3. After the install, but prior to adding new adhesive strips, consider temporarily putting the display back in place using painter's tape, and boot to make sure everything is working well. This beats adding new adhesives strips, getting everything glued up, just to find out that the SATA cables are not properly seated and your drive won't mount.

4. Consider a new Fusion Drive with your new SATA SSD and the OEM SSD from your old Fusion Drive. Once everything is working on your new drive, if you want to increase the speed, you can make your own Fusion Drive using Apple's SSD and the one you added. Apple's SSD is really fast in your model iMac, and the SATA SSD is a lot faster than your HDD, but doesn't compare to the OEM SSD. Fusing them together gives you the best the both world, a large capacity that is still super fast.

A lot of people do not like the last one, as they get scared for some reason like it might fail, but if your OEM SSD is in good shape, no reason to be scare. The huge majority of Fusion Drives fail because of the HDD, not the SSD, so no reason to be scare if you have a two SSD Fusion Drive.


Anyways, good luck on the SSD install!

Some very good ideas. Thanks.

Questions:

1) Makes sense. I'll see if I can get one prior to starting.
2) Doesn't this remove the recovery partition? If so, I guess I would have to do an internet install. Right? Not a problem, just trying to understand. I still have the external hard drive that I can boot from if required.
3) I've seen that in videos. Good advice and I'm going to do that. I like the painter's tape.
4) I'll look into that. My internal SSD is in good shape according to DriveDX. My assumption is that if I boot off of the external hard drive, I can un-fuse the drives from the command line. If this deletes the recovery partition, then I'd have to install the SSD, boot from the external drive and fuse them again. Then install to the SSD. Right?

Thanks!

 

[-paradox-]

If you‘re opening up your iMac, make it count:
Don‘t use an ifixit SSD. Take out the old (maybe faulty) blade and replace it.

Get a firecuda 530 NVME blade (I’ve tested it, full bandwidth) and an SSD (crucial / Samsung / sandisk - SSD for extra storage if needed) instead.

Enable trim support after install.

Your iMac will be incredible fast with the blade (vs SSD: Will be slower than Fusion Drive).

 

[YoitsTmac]

I had a client with a similar failure. I gave them a more pedestrian solution (2.5" SSD external enclosure through USB 3), but for a power user like yourself, this is what I recommend.

Although a Samsung T5 is a good drive, I personally would want more serviceable hardware.

OWC External Drive Enclosure via Thunderbolt for maximum bandwidth (link to Amazon), which conveniently includes a mount for you to mount it to your iMac.

Samsung NVMe 970 Evo Plus 2TB - or whatever size you'd like. (link to BHPhoto).

Then as the poster above stated, use your recovery or a USB and install it on the external SSD. They said to try fixing the new drive, but DriveDX kind of says it all...in my opinion storage is too cheap these days to try and make something work when it's trying to die . It sounds like you already have an off-device backup, which would be my only other recommendation.

 

[profcutter]

I had a client with a similar failure. I gave them a more pedestrian solution (2.5" SSD external enclosure through USB 3), but for a power user like yourself, this is what I recommend.

Although a Samsung T5 is a good drive, I personally would want more serviceable hardware.

OWC External Drive Enclosure via Thunderbolt for maximum bandwidth (link to Amazon), which conveniently includes a mount for you to mount it to your iMac.

Samsung NVMe 970 Evo Plus 2TB - or whatever size you'd like. (link to BHPhoto).

Then as the poster above stated, use your recovery or a USB and install it on the external SSD. They said to try fixing the new drive, but DriveDX kind of says it all...in my opinion storage is too cheap these days to try and make something work when it's trying to die . It sounds like you already have an off-device backup, which would be my only other recommendation.

The problem is they don't want to give up a thunderbolt port since they're using them for external monitors. Makes sense. In that way, only an internal drive will do what they need. The iMac Pros were expensive, but their main improvement was 4 thunderbolt ports.

 

[jbmillard]

The problem is they don't want to give up a thunderbolt port since they're using them for external monitors. Makes sense. In that way, only an internal drive will do what they need. The iMac Pros were expensive, but their main improvement was 4 thunderbolt ports.

Four ports - that would be nice.

The bottom line is that I need to get this computer running, even if it's only at the same speed it was before (which was fine). The iFixIt parts will be here today.

 

[Fishrrman]

OP wrote:
"I don't want external storage because I'd either have to run it on USB 2.0 or lose an external monitor which I don't want to do."

Those "other" USB ports on a 2019 iMac are USB3 (NOT "USB2")...

 

[Juicy Box]

2. Defuse or split the existing Fusion Drive (if you still can). Not doing this prior to install could cause boot problems.

2) Doesn't this remove the recovery partition? If so, I guess I would have to do an internet install. Right? Not a problem, just trying to understand. I still have the external hard drive that I can boot from if required.

Yes. I like to use CCC to make a bootable backup. This eliminates the need to use Internet Recovery, which sometimes doesn't work.

3. After the install, but prior to adding new adhesive strips, consider temporarily putting the display back in place using painter's tape, and boot to make sure everything is working well. This beats adding new adhesives strips, getting everything glued up, just to find out that the SATA cables are not properly seated and your drive won't mount.

3) I've seen that in videos. Good advice and I'm going to do that. I like the painter's tape.

Really? I honestly thought I came up with this one myself.

4. Consider a new Fusion Drive with your new SATA SSD and the OEM SSD from your old Fusion Drive.

If this deletes the recovery partition, then I'd have to install the SSD, boot from the external drive and fuse them again. Then install to the SSD. Right?

I am not 100% sure I am following what you are saying, but I think the concern is that creating a new Fusion Drive wipes anything that is currently on the drives, and that is correct.

As I said before, I like to use clones to work from, external clone that I boot from for troubleshooting, or if I am setting up a new drive, I will use a bootable back up clone. I highly suggest using this in place of TM or just an non-bootable back up.

But, you don't have to use clones, as there are multiple ways to do what you are trying to do, and not just the creation of the Fusion Drive part.

Do you have an external SSD? A thumb drive? a SD card? Even an old HDD?

You can install a fresh MacOS onto one of the above. After install, boot into and set up the OS (only takes a few minutes), but don't copy any of your BU files over, just use it as a way to boot into your Mac while you are doing work to it.


Also, I am not sure this will help you as I am not sure I am understanding your question, you can create a Fusion Drive with the new SSD and the existing SSD prior to even opening your iMac. If you connect your new SSD externally, defuse the existing Fusion Drive, you can set up the new Fusion Drive with the new SSD connected externally and the OEM SSD, make sure it works okay, and then open you iMac to do the install. I never done this, but in theory it should work. Although, I guess you run into the same issue about internet recovery.

 

[jbmillard]

Also, I am not sure this will help you as I am not sure I am understanding your question, you can create a Fusion Drive with the new SSD and the existing SSD prior to even opening your iMac. If you connect your new SSD externally, defuse the existing Fusion Drive, you can set up the new Fusion Drive with the new SSD connected externally and the OEM SSD, make sure it works okay, and then open you iMac to do the install. I never done this, but in theory it should work. Although, I guess you run into the same issue about internet recovery.

Thanks for the responses. I'm pretty convinced I can just about anything as long as I have internet recovery or a boot device. Since I still have the external boot drive I made, that will be my backup for recovery in case I wipe the recovery partition.

I'm going to start by defusing the drives, installing the SSD, and then fusing it with the existing (may not keep it that way, but I'll give it a try). It seems like I always end up doing things a couple of times anyway...

 

[akidd]

Thanks for the responses. I'm pretty convinced I can just about anything as long as I have internet recovery or a boot device. Since I still have the external boot drive I made, that will be my backup for recovery in case I wipe the recovery partition.

I'm going to start by defusing the drives, installing the SSD, and then fusing it with the existing (may not keep it that way, but I'll give it a try). It seems like I always end up doing things a couple of times anyway...

Best of luck. Hope it works. This is really what MR is for.

 

[Juicy Box]

Oh yeah, one other thing I forgot to mention for advice when opening up your Mac that you may not see in how-to guides.

When you’re finished everything and about to use your new adhesive strips to close up your Mac, use painters tape to hold the display onto the Mac body for a couple weeks. This gives the adhesive strips plenty of time to “cure”.

You see it occasionally on the forum, people do the swap that you’re doing, they get done with the new adhesive strips, close everything up, just to have their display fall off and break a few days later.


Also, make sure you do a good job cleaning up the old adhesive with alcohol before adding the new adhesive strips. That is probably almost the guides though, but worth mentioning due to the importance.

 

[Gudi]

.

 

[macguru9999]

I'm pretty sure you can't fuse a sata ssd and the pci one anyways. I tried once and it told me 'not supported' .... its generally not worth the trouble of replacing the mobo ssd unless you are very keen/handy... but you may think if you are already in there , why not ?... or, if you want to disable it, just format it apfs, then right mouse it in disk utility and delete the apfs volume. then it wont show up.

 

[profcutter]

I'm pretty sure you can't fuse a sata ssd and the pci one anyways. I tried once and it told me 'not supported' .... its generally not worth the trouble of replacing the mobo ssd unless you are very keen/handy... but you may think if you are already in there , why not ?... or, if you want to disable it, just format it apfs, then right mouse it in disk utility and delete the apfs volume. then it wont show up.

I’m not sure why you’re saying it’s a bad idea to replace the AHCI ssd. I’ve done it on MacBook pros, and there are entire threads on here telling you how to do it. Why are you advising against it? I’m genuinely curious.

 

[macguru9999]

I’m not sure why you’re saying it’s a bad idea to replace the AHCI ssd. I’ve done it on MacBook pros, and there are entire threads on here telling you how to do it. Why are you advising against it? I’m genuinely curious.

If I am doing an ssd for a customer, its not worth the trouble to pull the motherboard to install an ssd, just putting a sata ssd into the imac, 1,2 or even 4tb is a good upgrade and more profitable for me in terms of time spent. BUT if it was my OWN imac, then yes, I would replace the ahci ssd with an big nvme, as well as install a sata ssd volume. Sadly, the imacs i have here, a 2017 and 2019 21.5, do not have pcie slots on their motherboard, so i just added ram and 2tb sata ssds. There is a 27" 2015 here with that slot, but I have read they have wake from sleep issues with nvme drives, so if i ever do that one I have saved a 1TB ahci apple drive for the job.

 

[profcutter]

Ah ok, that does make sense. The OP obviously has the slot because they have a Fusion Drive. I suppose that’s why folks are replacing their CPUs at the same time on the iMac thread, because by the time you’ve got it all apart, the CPU is right there in a socket staring at you.

 

[macguru9999]

Ah ok, that does make sense. The OP obviously has the slot because they have a Fusion Drive. I suppose that’s why folks are replacing their CPUs at the same time on the iMac thread, because by the time you’ve got it all apart, the CPU is right there in a socket staring at you.

Yep, my 2019 I got for free had a cpu fault, it was only clocking 0.8ghz. so i changed the cpu and added more ram. But if i get a 2019/2020 ill add a 2gb nvme boot drive and a 4tb sata at the same time. all the 2020 ones still have that sata port on the mobo as well

 

[profcutter]

Yep, my 2019 I got for free had a cpu fault, it was only clocking 0.8ghz. so i changed the cpu and added more ram. But if i get a 2019/2020 ill add a 2gb nvme boot drive and a 4tb sata at the same time. all the 2020 ones still have that sata port on the mobo as well

I think the 2020s eliminated the AHCI port, and replaced it with a soldered drive. The SATA port may still exist, but the NVME option is over, if I’m not mistaken.

Ah, looks like no SATA connector either on the 2020.

 

[macguru9999]

I think the 2020s eliminated the AHCI port, and replaced it with a soldered drive. The SATA port may still exist, but the NVME option is over, if I’m not mistaken.

Ah, looks like no SATA connector either on the 2020.

Right, I see that now, thanks. Looks like 2019 is the pick of the bunch in terms of upgradeability and should run the next mac os, with the 2017 models a close second. I would not buy any older ones at this stage...

 

[profcutter]

Right, I see that now, thanks. Looks like 2019 is the pick of the bunch in terms of upgradeability and should run the next mac os, with the 2017 models a close second. I would not buy any older ones at this stage...

Yep, agreed. Any older and you lose Thunderbolt 3, and have TB2 instead, which is kind of a dead end. It’s much easier to find peripherals for TB3. If you’re looking to convert one for a display only though, a 2015 is probably fine.

 

[jbmillard]

Update...

The iFixIt kit arrived today. USP is getting better - they're two day shipping only took six days.

It took me about an hour to get the monitor off and get the SSD installed and get the monitor reconnected. I installed the adhesive strips, but I have not pulled the outer covers off of them yet. I'm making sure everything works before I do that. I have the monitor on the computer with painter's tape on four sides. I wouldn't move it like this but so far so good.

Removing the monitor was surprisingly easy. It only took a few minutes. The iFixIt tool used to cut the adhesive worked very well and they include a couple of cards to insert into the corners (after you have cut the adhesive) to keep them separated. The adhesive at the bottom was harder to separate, but you just have to keep after it and it finally separated. The only thing I'm worried about is when I pull the covers off the adhesive strips, I'll have to get it aligned just right. We'll see.

I booted off the external drive I made and opened a terminal. I used "diskutil resetFusion" and it fused the two SSDs in just a few seconds. The new one is 2 TB and the one on the motherboard is 121 GB (or they're about) and fused size was 2.12 TB. I'm now booting into internet recovery mode and will attempt to recover everything from my backups.

After I booted the first time, I opened diskutil and looked at the SSDs. The 121 GB SSD was "unrecognized". I'm assuming that's because it was fused with the dead hard drive I just pulled out.