24gb vs. 40gb for new iMac

ks-man

macrumors 6502a
Original poster
Sep 25, 2007
726
9
I'm planning on getting an entry level 27" and debating if I should buy an extra 16gb or 32gb to go with the initial 8gb. I'm not doing anything major on this computer so my instinct is to just get to 24gb but didn't know if people thought that I'm far better off with 40gb. Looking at Crucial and Amazon it seems I can get 16gb for $150 (Crucial) or 32gb for $275 (Corsair on Amazon).

Thanks for the any advice.
 

paulryp

macrumors regular
Sep 22, 2016
138
132
24gb is way more than any mortal could possible need or use. If need more than 24gb you would know why. The SSD part of the story is much more important.
 

jerwin

macrumors 68020
Jun 13, 2015
2,457
4,451
If you don't do anything major with your mac, you're going to wonder when your machine will finally get around to using more than 16GB of RAM. At the moment, my machine is using 10 GB plus 5.0 GB of speculative cache.

Go for the 24GB configuration.
 

theluggage

macrumors 601
Jul 29, 2011
4,034
2,717
24gb it is. Thanks!
16GB would be the sensible size for most people buying a new 5k iMac but since it's cheaper to get an extra 16GB from Crucial and end up with 24GB, that's probably the sweet spot.

...and if you're "not doing anything major" there's probably no rush to get the 24GB, since you can upgrade at leisure as/when you need it, and there's a lot of "nothing major" that can be done with 8GB. My advice: spend your money on the biggest SSD your budget will accommodate, even if you have to save up and get the extra RAM later.

In general use, the main thing surplus RAM gets used for is caching files to reduce delays caused by disc access - having most of your files on a super-fast SSD rather than spinning rust will help there, too.

If all-SSD is too expensive then at least get the 2TB Fusion option which has a much larger SSD cache.
 

jerwin

macrumors 68020
Jun 13, 2015
2,457
4,451
...and if you're "not doing anything major" there's probably no rush to get the 24GB, since you can upgrade at leisure as/when you need it, and there's a lot of "nothing major" that can be done with 8GB
web browsing on a 5k screen tends to kick the RAM usage into high gear. Not enough to use more than 16GB, but certainly enough to make 8GB feel less than optimal.

The thing is-- there are programs that don't need much RAM (Mail, Pages, disk utility, scrivener), and there are programs that like having a couple gigs (safari, Abby Finereader, xcode, eclipse). And then there are adobe products and virtual machines and video production stuff.

so, normal users on a small mac might be perfectly comfortable with 8gb and not see any swapping or memory compression
same work load on an imac 5k-- maybe 9-10 gb (of course this depends on how many tabs and windows you use). Which is more than 8GB, but not seriously even close to 16GB

it's not until you start dedicating 8gb to a virtual machine, or dedicating a couple gigs to photoshop that things start to get seriously cramped. Remember-- 16 GB is twice that of 8GB. Finding a legitimate use for memory beyond that is difficult unless you have already identified a specific need such as "photoshop with an enormous number of layers"

The 24 GB configuration is cheap enough that it feels roomy over just getting 16 GB
The 40 GB configuration is expensive enough that it's a waste of money.
 
Last edited:
  • Like
Reactions: KtothaEvin

BasicGreatGuy

Contributor
Sep 21, 2012
11,674
10,709
In the middle of several books.
I got 32GB of Corsair Vengeance (for a iMac total of 40GB) from Amazon for $221. I have been happy thus far, even though it was $70 dollars more than the 16GB.

Amazon is up and down on the price. I suggest going to camelcamelcamel.com, putting in the amazon URL of the size you want, and it will show you what the lowest price has been for it, as well as the average and third party prices. It will also alert you when the price is within your designated price range, if you provide your email. I use the site a lot and it has saved me a lot of time and money.
 
Last edited:

scotttnz

macrumors 6502a
Dec 16, 2012
533
1,966
Auckland, New Zealand
I asked myself the same question. I analysed my current usage (My Mac Pro has 24GB) and found that I was peaking at about 20GB used. That is with all the apps I would normally have open running simultaneously. Outlook, Word, Excel, Lightroom, Photoshop Elements, Safari with 10 tabs, some messaging apps, and a Parallels Windows 8.1 VM with a couple of Windows only tools that I use when working from home. I concluded that I would get no benefit at all from going to 40GB, so i'll upgrade to 24Gb when I get my iMac.
 

colodane

macrumors 6502a
Nov 11, 2012
789
254
Colorado
For your usage 24 GB is indeed the sweet spot. More than enough.

I got a 32 GB kit for mine to bring it up to 40 GB. This was purely "just because". Kind of wanted a "splurge" somewhere in the machine.

My usage is also not very demanding. Lots of web pages open sometimes, but no real heavy duty processing applications. I think the most memory I've ever seen in use was 18 or 19 GB and iStat always reports a memory pressure of either 7 or 8 %.

I think you will be just fine with 24 GB.
 
  • Like
Reactions: thewiccaman

jzuena

macrumors 6502a
Feb 21, 2007
997
31
Lexington, MA, USA
I have the base 27" and as others have mentioned I used my upgrade money on a 512GB SSD. I do run VMware Fusion virtual machines, so I knew I needed more than 8 GB (my Boot Camp Windows 10 alone gets 8 GB of memory). The cost difference between 8 and 16 GB from Crucial was minimal, so I got 16 GB for a total of 24 GB. I haven't had any memory issues.
 

thingstoponder

macrumors 6502
Oct 23, 2014
354
338
I'm planning on getting an entry level 27" and debating if I should buy an extra 16gb or 32gb to go with the initial 8gb. I'm not doing anything major on this computer so my instinct is to just get to 24gb but didn't know if people thought that I'm far better off with 40gb. Looking at Crucial and Amazon it seems I can get 16gb for $150 (Crucial) or 32gb for $275 (Corsair on Amazon).

Thanks for the any advice.
Why upgrade at all? Just keep the 8GB until it doesn't suit you anymore. I'm still on 4GB (1.5GB going towards the GPU) and doing fine. People on here vastly overplay the amount of RAM you need. The only time you need more RAM is if your memory pressure is consistently red in Activity Monitor.

I recently did a Ram test on my machine in which I opened every app (including large apps like Davinci, iMovie, Affinity Photo, Affinity Designer), and only after the last couple large apps opened did my machine start truly running out of RAM. I had video projects playing and it continued to work without a hitch. It was eye opening.
 
  • Like
Reactions: Cashmonee

SaSaSushi

macrumors 601
Aug 8, 2007
4,079
470
Takamatsu, Japan
If you are going to be doing 4K editing on a regular basis, along with having other apps running, I would go with 40GB. I like knowing I have enough, versus having to closely monitor and or worry I am cutting it close on RAM usage.
I agree. The same advice goes to those who need to run virtual machines. Because I need some Windows-only programs for my work, I often keep a Windows 10 Parallels VM running and 40GB means I never have to worry about RAM, no matter how many apps/windows I've got open at any given time in both OSes. I subscribe to the school of not enough RAM being a problem, not having some to spare. I also foresee a future where 64GB might be a reasonable upgrade.
 

mpConroe

macrumors regular
Feb 14, 2017
199
128
Arbroath (UK) / Wroclaw (PL)
I just checked my memory usage in Activity Monitor and it said about 16GB with Safari and Media Encoder rendering in the background. I have installed 40GB of RAM and I can say that for now - first day of usage - I'm happy with that. I hope it will be fine for more advanced video editing, capturing games and streaming...
 
Last edited:

jerwin

macrumors 68020
Jun 13, 2015
2,457
4,451
If you use Safari then you'll want 40GB on RAM.
That's only if your Safari Networking process starts to leak memory. In my experience, it starts clobbering CPU way before it exhausts RAM. Since it's a bug, YMMV.
 

tgara

macrumors 6502a
Jul 17, 2012
993
2,733
Connecticut, USA
If you don't do anything major with your mac, you're going to wonder when your machine will finally get around to using more than 16GB of RAM. At the moment, my machine is using 10 GB plus 5.0 GB of speculative cache.

Go for the 24GB configuration.
What is speculative cache? I ask because I have 24 GB installed in my new iMac, and according to CleanMyMac 3, I routinely use about 14-15 GB of RAM, leaving about 9 GB for other things. At first I was a bit surprised and concerned that I was using this much RAM running essentially only Mail and Safari, and was considering getting bigger chips. Maybe not?
 

ApfelKuchen

macrumors 68040
Aug 28, 2012
3,142
1,803
Between the coasts
What is speculative cache? I ask because I have 24 GB installed in my new iMac, and according to CleanMyMac 3, I routinely use about 14-15 GB of RAM, leaving about 9 GB for other things. At first I was a bit surprised and concerned that I was using this much RAM running essentially only Mail and Safari, and was considering getting bigger chips. Maybe not?
What "other things?" A Mac will "use" as much RAM as you have - it simply keeps loading new stuff without clearing out the old stuff, until it runs out of RAM. Then it starts removing old, unused items to make room for new. Chances are you don't even "need" all 14-15 GB - there's probably a lot of stuff that was loaded a while ago, used once, and hasn't been needed since.

I have 16 GB RAM, and have put it to some pretty heavy use (though not for video/audio production). The only time I've had a problem with RAM (significant swap used, abnormal memory pressure) is when there was a misbehaving app or web page.

Sure, RAM is cheap, so if you're going to pay Apple to have 16 GB, why not get 24 for the same price? But this isn't a matter of need. Why don't people simply buy an extra 8 GB at a lower price, and pocket the savings, or apply that savings to something else, like improved GPU/VRAM?

FWIW, memory management (or perhaps purely Safari inactive tabs improvements?) has been running even better under the High Sierra beta - I'm typically running Memory Used at 12-13 GB, and the Memory Pressure is a thin, green sliver at the bottom of the graph.
 

jerwin

macrumors 68020
Jun 13, 2015
2,457
4,451
What is speculative cache?
Some algorithm tells the kernel that you might need to reload or load a file from disk. So if you do, it's really fast (because it's already in memory). If you don't, it's just occupying space (which you may or may not need).
 
  • Like
Reactions: tgara

octatonic

macrumors regular
Mar 23, 2010
243
8
London
I have 40gb in mine, I do audio work so loads of plugins and sample libraries.
I would absolutely not buy Apple RAM, I got the base model and upgraded with OWC RAM.

I would prioritise a large SSD over more than 16GB RAM though.
 
  • Like
Reactions: tgara

tgara

macrumors 6502a
Jul 17, 2012
993
2,733
Connecticut, USA
Some algorithm tells the kernel that you might need to reload or load a file from disk. So if you do, it's really fast (because it's already in memory). If you don't, it's just occupying space (which you may or may not need).
Great, thanks. I'll keep an eye on memory usage and if it keeps hitting max, I might add more.
 

kdoug

macrumors 6502a
Jun 2, 2010
969
119
Iowa City, IA USA
I originally purchased 16gb Crucial Mac memory from Amazon for $160 and then realized that 32gb from B&H was only $100 more. In the long run I think 32gb made the most sense.
 

EugW

macrumors 604
Jun 18, 2017
7,302
4,687
I originally purchased 16gb Crucial Mac memory from Amazon for $160 and then realized that 32gb from B&H was only $100 more. In the long run I think 32gb made the most sense.
Most sense for what? I'd rather just save the $100 since 24 GB for me will be enough for the life of the machine. In contrast, 24 GB isn't enough for some people even right now. It really depends on your current and projected future usage habits.

I did go with 16 GB for my MacBook though. I don't actually need 16 GB in my MacBook any time soon, but occasionally may need more than 8 GB. However, because I can't get say 12 GB in a MacBook, I went with 16.
 

kdoug

macrumors 6502a
Jun 2, 2010
969
119
Iowa City, IA USA
Most sense for what? I'd rather just save the $100 since 24 GB for me will be enough for the life of the machine. In contrast, 24 GB isn't enough for some people even right now. It really depends on your current and projected future usage habits.

I did go with 16 GB for my MacBook though. I don't actually need 16 GB in my MacBook any time soon, but occasionally may need more than 8 GB. However, because I can't get say 12 GB in a MacBook, I went with 16.
Well, for ONLY $100 more you get TWICE the memory. For ME that makes the most sense. Down the road, if I want to MAX out he memory, another 32GB will do the trick.
It's the same argument when it comes to i5 vs i7 and 512SSD vs 1TB SSD. I also chose the latter.
Will I need it? Probably not. Do I want it? HECK YES!
 
  • Like
Reactions: rotlex