iMac 2019 slow - Considering buying RAM

digitalove

macrumors regular
Original poster
Jun 12, 2012
194
1
Hello there!

I recently bought a iMac21.5 2019 Retina 4k
- i3 quad-core 3.6 GHz
- 8 GB 2400 MHz DDR4
- Radeon Pro 555X 2 GB
- 1 TB (Not SSD)

The iMac while doing multitasking often lags a bit, nothing serious but still something you wouldn't expect from a new iMac. It's not as responsive as I thought.

I'm not sure if the problem is the HD which is slower than the SSD or the little RAM it has. I guess it's the RAM.
  • Do you think adding 8 GB RAM would improve the time of response of multitasking?
  • If so, this ram is compatible?

Thanks =)
 

TwoH

macrumors regular
May 19, 2019
183
65
Nope, that is DDR3 RAM, you are after DDR4 2400MHz RAM.
SSD would help big time compared to a 5400RPM HDD. 8GB RAM is decent for what it is - should be able to do a good amount of tasks with no issue, unless you're working on something such as music.
And to change the RAM or HDD in a 21.5" - be prepared to take the LCD off the iMac.

Edit: 21.5" only have 2 RAM slots too, not 4.
 

tyc0746

macrumors regular
Apr 3, 2019
168
53
Liverpool, UK
More memory may help, but it depends what it's multi-tasking at! 4 internet tabs...easy. Trying to encode 4 streams of 4k video...not so easy.

The combination of slowest processor, least cores, non-SSD, Catalina...all add to the slowness!

You can't easily upgrade the RAM as there's no door at the back in the 21.5" models. I'd return it and pay the extra for 16GB, i5, and small SSD. Or you can always keep an internal HD if you're willing to buy a fast external SSD to boot from.
- - Post merged: - -

 

gian8989

macrumors 6502
Oct 23, 2015
273
77
The RAM is your last problem. 8GB are more than enough for any daily basic task. On the other end the HDD is just terrible for macOS. You can have the best hardware but with that hdd it will always be slow. So you have 2 choice:
1. return and buy one with ssd
2. buy an external ssd and install the OS in it.
 
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mckenzzzzie

macrumors newbie
Jun 22, 2020
2
1
1. return and buy one with ssd
I agree with this course. If you can't return, then sell. Apple should not be selling spinning HDs in any of their computers at this point. The performance of recent versions of the OS is seriously not optimized for it, even beyond the inherent slowness of a spinning drive. The good news is that if you picked up a Mac with an SSD (and it doesn't even have to be that large if it's a desktop) and 16 GB of RAM, it will easily last you many years. Just hook up an external drive if you really need a lot of storage.
 
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FSMBP

macrumors 68030
Jan 22, 2009
2,517
1,417
Hello there!

I recently bought a iMac21.5 2019 Retina 4k
- i3 quad-core 3.6 GHz
- 8 GB 2400 MHz DDR4
- Radeon Pro 555X 2 GB
- 1 TB (Not SSD)

The iMac while doing multitasking often lags a bit, nothing serious but still something you wouldn't expect from a new iMac. It's not as responsive as I thought.

I'm not sure if the problem is the HD which is slower than the SSD or the little RAM it has. I guess it's the RAM.
  • Do you think adding 8 GB RAM would improve the time of response of multitasking?
  • If so, this ram is compatible?

Thanks =)
As others said, I would vote for an SSD. As your iMac's RAM/HD are not easily accessible, look into booting off an external SSD (maybe connector via Thunderbolt).

I do believe you can go to an Authorized Apple Repair Shop and get the RAM upgraded. I imagine this will be expensive.
 
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Spectrum

macrumors 68000
Mar 23, 2005
1,614
934
Never quite sure
Check activity monitor > RAM and look how much RAM you are regularly using and how much is swapping. Post a screenshot.

The main issue is the HDD, and especially if you are swapping to disk regularly. If so, more RAM will help.

However, a better solution would be to get an external USB3 SSD and boot the system from that. The difference will be like night and day.
 
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sracer

macrumors G3
Apr 9, 2010
8,640
9,312
Prescott Valley, AZ
The RAM is your last problem. 8GB are more than enough for any daily basic task. On the other end the HDD is just terrible for macOS. You can have the best hardware but with that hdd it will always be slow. So you have 2 choice:
1. return and buy one with ssd
2. buy an external ssd and install the OS in it.
This. I recommend #2. That is what I did with my 1TB spinner iMac. It is so much faster than it ever was... the difference is shocking. Starting MS Office from the harddrive required 56 bounces of the icon + 10 seconds. From the external SSD, 5 bounces.
 

jerwin

macrumors 68030
Jun 13, 2015
2,771
4,605
It’s far more likely that your cpu is waiting on your hard drive than anything else. An external SSD (Sara plus usb enclosure will do, unless you plan on editing video) is your best bet.

If, however, you do things like render videos, or run scientific simulations, or do a lot of image processing, and the iMac’s speed is limiting the number of things you can do in a day— that’s when a gpu or cpu upgrade is called for.

memory is sort of a black box. activity monitor’s memory pressure is helpful here.
 

26139

Cancelled
Dec 27, 2003
4,315
370
It's the HD.

My dad's 2016 (I think) iMac with 8 gigs of ram, that came with an HD, is now running an SSD and it works just as well as any modern computer for normal stuff.

Before that, beachballs fairly regularly, even though they did go away fast.

It feels like the last two Mac OSes have been specifically built to run off of SSDs.
 
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bousozoku2

macrumors newbie
Jun 22, 2020
16
6
Lard
I agree with this course. If you can't return, then sell. Apple should not be selling spinning HDs in any of their computers at this point. The performance of recent versions of the OS is seriously not optimized for it, even beyond the inherent slowness of a spinning drive. The good news is that if you picked up a Mac with an SSD (and it doesn't even have to be that large if it's a desktop) and 16 GB of RAM, it will easily last you many years. Just hook up an external drive if you really need a lot of storage.
I'm using a mid-2012 MacBook Pro with 1TB SSD and 16GB of RAM with a 3rd generation i7 and GeForce 650M and it's fine on Catalina but with the hard drive and low RAM, it was barely functional.
 
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bousozoku2

macrumors newbie
Jun 22, 2020
16
6
Lard
It's the HD.

My dad's 2016 (I think) iMac with 8 gigs of ram, that came with an HD, is now running an SSD and it works just as well as any modern computer for normal stuff.

Before that, beachballs fairly regularly, even though they did go away fast.

It feels like the last two Mac OSes have been specifically built to run off of SSDs.
It's APFS, the replacement for HFS+, that is the problem.
 
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Spectrum

macrumors 68000
Mar 23, 2005
1,614
934
Never quite sure
Anyway...I just noticed. This is a 21 inch 4K iMac. Upgrading RAM is not trivial.
By far, your simplest option is to boot from an external SSD.
 
Last edited:

Fishrrman

macrumors Core
Feb 20, 2009
19,390
6,703
Adding RAM is NOT going to speed this one up very much, if at all.
You can't add RAM to a 4k iMac in any case, without completely DISASSEMBLING the computer.

Your problem is the drive itself:
It's a platter-based hard drive. These can run excruciatingly slow on Macs running modern versions of the OS.

The solution:
You probably don't want to pry this open to replace the internal drive.
So...
The better, faster, easier, SAFER way to do it is to buy a USB3 SSD, plug it in, and set that up to become "the new external boot drive".

Do this, and it will run MUCH faster.

Actually, I suggest you consider a USB3.1 gen2 enclosure like this:

...and put into it an nvme blade SSD like this:

This will give you a boot drive with read speeds of about 965MBps and writes in the 860MBps range.

Putting together a drive like this is so easy, anyone can do it (even I was able to do it).

It will completely TRANSFORM the iMac.
You'll come back here and post that you can't believe the difference it makes...
 
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