slow iMac 27" mid 2019 - will updating memory change performance?

[tomsop]

I have a 3 GHz 6 core Intel I5 processor and Radeon Pro 57x 4GB graphics with 16 GB DDR4 ram. However the ram is split into 4 - 4GB modules - I am pretty sure I ordered it with 16GB of ram.

The machine is really slow. I experience it most when loading apps and upon startup if I had shut down with a lot of applications open and it has to reload the apps - or just in general it is slow when launching ThinkorSwim trading software for example.

I was wondering if having the ram split into 4 modules is causing the slowness - would it be better to upgrade there ram into 2 8GB modules for example.

I have about 700GB worth of stuff loaded onto the fusion 1TB drive but I assume that having 300GB of free space should not be causing slowness issues. Any suggestions?

 

[Nguyen Duc Hieu]

1. Buy an external SSD drive, USB 3.0 box is enough.
2. Move all your stuffs to the external drive, including the Mac OS. (You are supposed to know how to move the Mac OS and personal stuff to the external drive)
3. Boot from the external drive and enjoy the smoother experience using SSD.

 

[tomsop]

Thank you - I am willing to give that a try - I do not know how to move OS to an external dive and have that as the boot drive - is there a resource you recommend for instructions on how to accomplish that? If not, that is okay - I do appreciate the suggestion.

 

[JonaM]

I'd second that - the speed increase from switching mine to an external SSD drive was amazing

 

[Bigwaff]

I have about 700GB worth of stuff loaded onto the fusion 1TB drive but I assume that having 300GB of free space should not be causing slowness issues. Any suggestions?

The issues you describe are the symptoms of a Fusion Drive failing. Most likely the SSD component. Fusion Drives notorious for failures as they hammer the tiny SSD used as fast access cache for HDD files. As suggested above, replace HDD w/ SSD or use external SSD as boot drive.

 

[DeltaMac]

The RAM is unlikely to be causing the slowdown, although you could run the built-in diagnostics to check if anything is reported. Replacing the 2 sets of 4GB pairs with 2 x 8GB will not likely make any noticeable difference
Plus, you don't need to limit yourself to only 16GB - your 2019 iMac can use up to 128GB, should you conclude that 16GB is not really enough.

More than likely, the cause of your slowdown is the boot drive, the Fusion drive. That is composed of two separate devices: an SSD, which will be a small capacity -- a 1TB fusion drive will have a 32 GB SSD, used basically for booting. Much of your apps and files will be stored on the (spinning) hard drive.
Now that you have some age on the iMac hardware, one or the other part of the Fusion drive may be giving you problems. Might not be a major problem, but the result is often a noticeable slowdown.
You can bypass that easily by plugging in an external SSD (size would be your choice), then transferring your system+your apps and files to that external SSD. Easiest way to do that, after adding the external drive, is to install your macOS system on that external drive. That gives you a clean install of the system. You can go from there, moving whatever you need, but you can also copy eveything at once. At the end of the install, your new system will ask if you want to transfer files, data, and settings from the old drive. You can choose to do that, just follow the steps to choose your internal boot drive, and system will take over by migrating everything from the old drive. Be patient, the migration can take an hour or more, depending on how much is stored on your fusion drive. The system will let you know when the migration is complete.

 

[Nguyen Duc Hieu]

Thank you - I am willing to give that a try - I do not know how to move OS to an external dive and have that as the boot drive - is there a resource you recommend for instructions on how to accomplish that? If not, that is okay - I do appreciate the suggestion.

It will cost you some money to use CCC (carbon copy cloner), but it's hassle free and you can use a SSD smaller than 1TB.

Download Carbon Copy Cloner | Carbon Copy Cloner | Bombich Software

bombich.com

Apple Disk Utility is free, but it requires your SSD to be the same or bigger than 1.03TB (i.e 2TB SSD), and it takes several hours at least to move your files. Much longer than CCC.

 

[ThunderSkunk]

I was thinking of trading my SSD iMac27 for the same model with a hybrid drive just so I could split the drive, toss a 4TB M2 stick in it and an 8TB Sata ssd in place of the slow spinny disc, not recombined them as hybrid, but just contain it all in a single tidy package. 4tb for working, 8tb for footage archive. But then I realized you can get a SATA+Power cable from OWC for like $20 or whatever it was, so I got that, sure enough found the plugs to add the extra internal SATA drive to my SSD Only iMac's board, and viola, 2 internal drives. ...but then, funny old thing, but the sata ssd would occasionally not be writable. Then I'd reboot and it might be fine again. Might be. Started getting read write errors on it, and gave up, pulled the drive and went back to SSD only, simple and reliable.

I guess OP could have his failing hybrid drive pulled and just put a single SSD in it & skip the additional sata drive. That way it'd just behave like a normal SSD-only iMac & not hammer the nvme feeding the sata drive.

 

[Nguyen Duc Hieu]

I was thinking of trading my SSD iMac27 for the same model with a hybrid drive just so I could split the drive, toss a 4TB M2 stick in it and an 8TB Sata ssd in place of the slow spinny disc, not recombined them as hybrid, but just contain it all in a single tidy package. 4tb for working, 8tb for footage archive. But then I realized you can get a SATA+Power cable from OWC for like $20 or whatever it was, so I got that, sure enough found the plugs to add the extra internal SATA drive to my SSD Only iMac's board, and viola, 2 internal drives. ...but then, funny old thing, but the sata ssd would occasionally not be writable. Then I'd reboot and it might be fine again. Might be. Started getting read write errors on it, and gave up, pulled the drive and went back to SSD only, simple and reliable.

I guess OP could have his failing hybrid drive pulled and just put a single SSD in it & skip the additional sata drive. That way it'd just behave like a normal SSD-only iMac & not hammer the nvme feeding the sata drive.

I would NOT advice a newbie who doesn't know how to clone his drives to physically open his iMac and replace anything inside. Just doing the simplest thing of plugging in an external SSD seems to be a hard task for him already.

 

[ThunderSkunk]

I agree, I was more thinking he'd take it in to a third party shop & have it done.

 

[Fishrrman]

OP wrote:
"I do not know how to move OS to an external dive and have that as the boot drive - is there a resource you recommend for instructions on how to accomplish that? If not, that is okay - I do appreciate the suggestion."

Changing the RAM probably won't do anything for the speed.

The "speed problems" are probably based in the fusion drive -- as others have suggested.

I'll tell you EXACTLY how to make the move to an external SSD boot drive.
But you have to be willing to follow my instructions.
PRINT OUT this reply and save it -- you will need it.

I believe a 2019 iMac has USB3.1 gen2 ports on the back (2 USBc ports).
So... for the best speeds, you want a USB3.1 gen 2 drive.

I would recommend either of the following:
- Samsung t7 "shield", 1tb size (or 2tb if you don't mind spending a little more)
or
- Crucial X-9
The drive needs to be plugged into the USBc port on the back (NOT an "a" port) in order to achieve the best speeds (which will be around 850-900MBps on USB3.1 gen2).

When you get the drive, connect it to the iMac.
Open disk utility.

VERY important step -- in disk utility, go to the "view" menu and choose "show all devices".

Locate the SSD, click it (make sure you select the physical media), and then click erase.

YOU DIDN'T TELL US WHICH VERSION OF THE OS YOU'RE USING.
I'm going to GUESS that it needs APFS.
So, after you click "erase" select "APFS".
Now, erase the drive.

It's ready for the next step.

Download SuperDuper by clicking this link:

https://shirt-pocket.com/mint/peppe...://shirt-pocket.com/downloads/SuperDuper!.dmg

SuperDuper is a drive cloning app and it's FREE TO USE for what we're going to do with it.

Open SD.
It has a VERY simple and easy-to-understand interface. Anyone can use this.

On the top line (copy), put your source (the internal fusion drive) on the left.
Put your target (the new SSD) on the right.

Accept the rest of the defaults and click "copy now".

For 700gb of stuff, this is going to take a while. BE PATIENT.

When done, quit SD.
Now, open the startup disk preference pane.

Do you now see TWO drives there (the internal and the external)?
Good, that's what we want.
Click the lock icon and enter your password.
Then click the external SSD and restart.
(on the latest versions of the OS, you click the drive icon first and THEN enter your password)

If things went as they should, you should now boot from the external SSD.
It will look EXACTLY like the fusion drive when you get to the desktop -- after all, "it's a clone".

Go to the "about this Mac" menu item (Apple menu).
It will tell you WHICH startup disk from which you're booted.
Is it the external?

Then congratulations, you're all done.

BE AWARE that with an external boot drive, you must now "back it up" as you would your internal drive.
If it was me, I'd keep using SuperDuper, and use the SSD as the source and the fusion drive as the backup.

Good luck.

 

[tomsop]

Thank you all for the replies - going to go this route. I had considered upgrading and getting the M3 but the cost of an external drive is cheaper and I do not see why I cannot get a few more years out of my iMac. The only intensive thing I do with this is Lightroom. All of the advice was really helpful and I will refer back to this thread when I am ready to proceed in the future.

 

[larry989]

OP wrote:
"I do not know how to move OS to an external dive and have that as the boot drive - is there a resource you recommend for instructions on how to accomplish that? If not, that is okay - I do appreciate the suggestion."

Changing the RAM probably won't do anything for the speed.

The "speed problems" are probably based in the fusion drive -- as others have suggested.

I'll tell you EXACTLY how to make the move to an external SSD boot drive.
But you have to be willing to follow my instructions.
PRINT OUT this reply and save it -- you will need it.

I believe a 2019 iMac has USB3.1 gen2 ports on the back (2 USBc ports).
So... for the best speeds, you want a USB3.1 gen 2 drive.

I would recommend either of the following:
- Samsung t7 "shield", 1tb size (or 2tb if you don't mind spending a little more)
or
- Crucial X-9
The drive needs to be plugged into the USBc port on the back (NOT an "a" port) in order to achieve the best speeds (which will be around 850-900MBps on USB3.1 gen2).

When you get the drive, connect it to the iMac.
Open disk utility.

VERY important step -- in disk utility, go to the "view" menu and choose "show all devices".

Locate the SSD, click it (make sure you select the physical media), and then click erase.

YOU DIDN'T TELL US WHICH VERSION OF THE OS YOU'RE USING.
I'm going to GUESS that it needs APFS.
So, after you click "erase" select "APFS".
Now, erase the drive.

It's ready for the next step.

Download SuperDuper by clicking this link:

https://shirt-pocket.com/mint/peppe...://shirt-pocket.com/downloads/SuperDuper!.dmg

SuperDuper is a drive cloning app and it's FREE TO USE for what we're going to do with it.

Open SD.
It has a VERY simple and easy-to-understand interface. Anyone can use this.

On the top line (copy), put your source (the internal fusion drive) on the left.
Put your target (the new SSD) on the right.

Accept the rest of the defaults and click "copy now".

For 700gb of stuff, this is going to take a while. BE PATIENT.

When done, quit SD.
Now, open the startup disk preference pane.

Do you now see TWO drives there (the internal and the external)?
Good, that's what we want.
Click the lock icon and enter your password.
Then click the external SSD and restart.
(on the latest versions of the OS, you click the drive icon first and THEN enter your password)

If things went as they should, you should now boot from the external SSD.
It will look EXACTLY like the fusion drive when you get to the desktop -- after all, "it's a clone".

Go to the "about this Mac" menu item (Apple menu).
It will tell you WHICH startup disk from which you're booted.
Is it the external?

Then congratulations, you're all done.

BE AWARE that with an external boot drive, you must now "back it up" as you would your internal drive.
If it was me, I'd keep using SuperDuper, and use the SSD as the source and the fusion drive as the backup.

Good luck.

I followed your instructions and it worked great, significant increase in speed and no spinning beachball, thanks

 

[AL2TEACH]

The machine is really slow.

My iMac is a 2015 and it was really slow. I took it to a shop and replaced the spinner with a SSD. It wasn't a day and night difference but it was a wow difference. I also use https://etrecheck.com/en/index.html. The way you use the puter, it should last you until you decide to upgrade and I'd think there's no rush. I thought about doing the SSD change myself and that was a no-no. If you decide to get a SSD see what ThunderSkunk(lol) said

take it in to a third party shop & have it done.

Yeppers on that one. That name just makes me chuckle lol.