Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

Upgrading from 16GB to 32GB on a Late 2015 iMac. Will I notice the difference?

superleccy

superleccy

macrumors 6502a
Original poster
Oct 31, 2004
997
187
That there big London
Hello. Sorry this is a bit of a lazy post but here goes.

I have an 27" iMac late 2015, 4GHz Quad Core i7, 16GB RAM, 1TB SSD, AMD Radeon R9 M395X 4 GB.

I have never had an issue with the performance of this machine, even to this day, after over five years. Apart from general Office stuff, I do a lot of work in Logic.

I have just ordered a couple of 8GB DDR3 RAM sticks to max out the RAM to 32GB. Thought "I may as well".

Will I actually notice any difference, given that I didn't have an actual problem with it before?

Cheers
SL
 
I have a 2019 iMac with the original 8 GB Apple RAM. I added 16 GB of OWC RAM and had intermittent system shut downs. I removed the original Apple RAM and all has been well for months. There seems to be incompatibility issues with some RAM even though they are specified to work.
 
Albert2011 said:
I have a 2019 iMac with the original 8 GB Apple RAM. I added 16 GB of OWC RAM and had intermittent system shut downs. I removed the original Apple RAM and all has been well for months. There seems to be incompatibility issues with some RAM even though they are specified to work.
Click to expand...
Oh bums. I've ordered OWC RAM. We shall see...
 
Since I got mine, it's slowed right down!! I bought a Crucial 4x8GB upgrade and a 1440p screen for my late '15 machine. Previously as solid as a rock in 16GB state. I got an all-in-one kit as opposed to just keeping the original 8s and adding 2 more. All of my Adobe apps have been playing up since, although I thought this may be down to the 2nd screen as the graphics card only gas 2GB VRAM. But removing the screen has made no difference. I'm holding off putting the old DIMMs back in, but if it comes to it, I'll have some chips you can buy!
 
  • Like
Reactions: superleccy
MacOS is exceptionally good at memory management. MacOS 10.15 Catalina & MacOs 11 Big Sur both require a minimum of 4GB RAM; I'm running Big Sur on a 4GB 2015 MacBook Air and it runs great, no complaints. I view 8GB as being practical; 16GB as being desirable; and 32GB as being excessive. Going from 16GB to 32GB I don't believe you'll ever notice any difference, unless you're maybe editing 8K video or something crazy like that. For 99% of Mac owners 8GB is all they'll really need.
 
If Activity Monitor, Memory tab, currently shows low memory pressure and little "Swap Used," it is likely you will notice little difference, especially as you have a 1TB SSD (which allows fast swap usage). If you use browsers (especially Chrome) with lots of tabs open, you might notice a difference with better caching of web pages.

One you upgrade the RAM, it will use more of the RAM (just because it can, for caching etc.), but that does not mean the performance will be noticeably faster.
I suggest run Novabench RAM speed test before and after upgrading, to check the RAM transfer speed. If it goes down, something is not right. (Run it several times and take the maximum score MB/s.)
 
Last edited:
  • Like
Reactions: superleccy
Okay. Memory installed. It's only been 24 hours but I've not been experiencing the shutdowns and slowdowns and problems that some have reported on this thread. It was fine before and it's fine now.

Performance improvement: None that I have noticed, although I haven't really taxed it yet. It's nice to see my activity monitor report 0 bytes Swap Used... but whatever.

Have I basically wasted a fistful of pound sterling on an unnecessary upgrade? Yeah, guilty as charged, probably. I just had two empty RAM slots in a 5 year old machine and thought it was about time. Lesson learned.

But it goes to show how remarkable Macs are when Apple get it right. I can't think of a 5 year old PC that would still feel this fresh after 5 years, RAM upgrade or not!
 
  • Like
Reactions: Geoff777, orbital~debris and wilberforce
superleccy said:
Performance improvement: None that I have noticed, although I haven't really taxed it yet. It's nice to see my activity monitor report 0 bytes Swap Used... but whatever.

Have I basically wasted a fistful of pound sterling on an unnecessary upgrade? Yeah, guilty as charged, probably. I just had two empty RAM slots in a 5 year old machine and thought it was about time. Lesson learned.
Click to expand...
Well, you now can leave more apps open simultaneously, more browser tabs and more documents. A room with no walls :)
 
  • Like
Reactions: orbital~debris and superleccy
superleccy said:
Okay. Memory installed. It's only been 24 hours but I've not been experiencing the shutdowns and slowdowns and problems that some have reported on this thread. It was fine before and it's fine now.

Performance improvement: None that I have noticed, although I haven't really taxed it yet. It's nice to see my activity monitor report 0 bytes Swap Used... but whatever.

Have I basically wasted a fistful of pound sterling on an unnecessary upgrade? Yeah, guilty as charged, probably. I just had two empty RAM slots in a 5 year old machine and thought it was about time. Lesson learned.

But it goes to show how remarkable Macs are when Apple get it right. I can't think of a 5 year old PC that would still feel this fresh after 5 years, RAM upgrade or not!
Click to expand...
If you use a lot of Adobe programmes - then you can go into the preferences and allocate more RAM to increase performance (might as well take advantage now you have it) -iirc the default allocation is 70% - I predominantly use LR and PS and they benefit massively from the ramp up in available memory.

Not sure what SSD you have? - but if it's just an SSD in place of the HDD - then you can increase the speed of your system by switching to an NVMe blade drive - just waiting on mine to arrive and will keep my Samsung EVO 870 as additional storage.
 
Thanks
cerberus1846 said:
If you use a lot of Adobe programmes - then you can go into the preferences and allocate more RAM to increase performance (might as well take advantage now you have it) -iirc the default allocation is 70% - I predominantly use LR and PS and they benefit massively from the ramp up in available memory.

Not sure what SSD you have? - but if it's just an SSD in place of the HDD - then you can increase the speed of your system by switching to an NVMe blade drive - just waiting on mine to arrive and will keep my Samsung EVO 870 as additional storage.
Click to expand...
Thanks. I don't do Adobe but I do a lot of stuff in Logic, and sometimes stupidly big spreadsheets. (I'm a rubbish music producer but a moderately competent Data Architect). Logic seems to be bound more by processor speed, but maybe it will help with the spreadsheets.

I have the built-in SSD that came with the iMac.
 
  • Like
Reactions: cerberus1846
ah ok... you've probably seen this - but there are some items that you might be able to configure to improve performance:

Avoid system overloads in Logic Pro for Mac – Apple Support (UK)

Find out what to do if a system overload alert interrupts playback or recording in Logic Pro.
support.apple.com support.apple.com

I'm a BA so deal with stupidly large data sets as well - thankfully, usually through a VM where the server does all the heavy lifting! ;) :)

Also, an option to consider for future would be adding an NVMe blade - as these are even faster than SSD's.. it's a fairly involved swap (as you need to strip down everything) but the performance gains are meant to be worth it.. currently I'm waiting on my blade drive arriving - so I'll post and let you know fi it's a worthwhile upgrade! :)
 
cerberus1846 said:
ah ok... you've probably seen this - but there are some items that you might be able to configure to improve performance:

Avoid system overloads in Logic Pro for Mac – Apple Support (UK)

Find out what to do if a system overload alert interrupts playback or recording in Logic Pro.
support.apple.com support.apple.com

I'm a BA so deal with stupidly large data sets as well - thankfully, usually through a VM where the server does all the heavy lifting! ;) :)
Click to expand...
Thank you for your reply. I've actually learned something. Much appreciated.
 
  • Like
Reactions: cerberus1846
A while back I upgraded the memory in my late 2014 iMac to 32 GB.

I am very sure that my usage does not really require so much memory. I seldom check memory usage on Activity Monitor and when I do, it's using a lot of the memory available (like > 50%) but not all.

Even though there is no real reason for me to have this much memory, it makes me feel better. There is a psychological benefit, I am convinced!

So don't fret if you've decided to get more RAM than you probably need. It will make you feel good, trust me!
 
  • Like
Reactions: superleccy
If I wasn't running Windows 10 on parallels, I wouldn't notice it. Definitely helps to have 32GB to throw at a VM (I give the VM 12+GB) - memory doesn't even hit 60% utilization. lol. With no parallels? I use like 10% of it.
 
Just for info, you might like to know that 32GB is NOT your maximum RAM.
The Late 2015 27-inch iMac will support 16GB in each slot, so max RAM is actually 64GB!
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back