How Much Memory for an iMac?

[CaptainBlue]

I currently use a 27" 2020 iMac with 3.8 GHz 8-Core Intel Core i7, AMD Radeon Pro 5500 XT 8 GB, and 128 GB 2667 MHz DDR4 RAM.

When/if the M4 iMacs are released in November, if they're like the present iteration of the 24" iMac, the maximum RAM would be 24 GB.

So would that be enough? I'm an Old School iMac user right back and you always whacked as much RAM in as possible with third party - i.e. cheaper - memory.

Other than the 'normal' Office work, I also use Lightroom and occasionally Photoshop for my photography, plus I also do some video editing occasionally using Final Cut Pro.

 

[HobeSoundDarryl]

When you ask Apple fans this question, you're going to get an overwhelming volume of answers that says whatever RAM Apple offers is the right amount of RAM... including base specs.

Odds are higher than typical that the long-term base spec of 8GB- which has passionately been argued as plenty for "most people" including anyone describing how you use your existing Mac- is probably going to step up to either 12GB and 16GB in just a few weeks. If so, these same people who have defended 8GB as "plenty" for all these years will not then rip Apple for "overloading" Macs with "too much" RAM but will instead just shift on to the new base specs as being "plenty," then potentially shifting to putting down 8GB as "too little" and thus the need to upgrade to what Apple is selling now.

Based on your description, the 8GB argument very commonly made could be made. And if base specs become 12GB or 16GB, that argument can be made (and is at least better than the 8GB argument).

However, I'll caution you to go at this not based on 2024 needs but based on life of device needs. How long will you keep this Mac before replacing it? Based on your post, your number appears to be at least 5 years. So attempt to anticipate what you'll be trying to do with this new Mac in 2029-30, NOT just 2024.

If that's still what you describe, base specs probably works for you. If you can anticipate anything that will be more RAM demanding, you may want to add more RAM. Unlike the Intel past, there is no adjusting this later... so you have to buy whatever you will EVER need... NOT what is "good enough" for now. Else, instead of adding some more cheap RAM later when you discover you need it, you have to buy a whole new computer.

Lastly, Apple Intelligence is going to need a lot of RAM... and Apple is probably going to be pushing and evolving it for the next few years. As more and more of it piles in, it will probably need more and more RAM allocations. None of us can reasonably estimate what that RAM need will actually be. So I'd build in a sizable "fudge factor" to try to cover that mostly unknown RAM need... even if you have some concept about not wanting to use it (because macOS will probably have many uses for it whether you want to do additional things with it or not). For example, for the most part, I just about NEVER use Siri... but Siri occupies OS space on all my Apple devices. A.I. will too... whether I want to use it or not.

My advice:

• Attempt very best effort at imagining your 2029-30 needs. More intense photo or video editing? Other interests that are RAM hogs? This is harder to do than it is to write down... but very important if you want to get this right.
• Once you know your probable number, round UP even if it is barely over some threshold that Apple chooses. For example, if you can anticipate a regular need for 17GB, think 24GB or 32GB- whichever is next tier up above 16GB. Liberally factor in the A.I. fudge. A working concept is Apple A.I. is going to need 8GB of RAM right up front, so assume 2029 will probably at least double that if not more... as macOS will evolve 5 times by then and A.I. is probably the "it" focus for the next few years at least.
• DO NOT trust opinions about leaning on SWAP. SWAP works just fine but it involves using SSD like slow RAM. SSDs fail after too many writes. See countless threads about problems with failing Fusion Drive Macs. In the majority of those cases what is making them fail is too many writes to the SSD portion. SWAP is basically doing the same- there's just more SSD space to potentially make this NOT be an issue during life of a device. Nevertheless, I would never lean on using SSD like RAM in this calculation. Instead, I'd see SWAP as "gravy" in very unusual circumstances when I overrun the right amount of RAM I've chosen. The same people who will argue FOR SWAP are likely the ones who argued that Fusion drives would be fine during life of those devices... and now we see post after post of failing Fusions and none of them are backing up their very passionate opinions back then. Instead, it's just "buy a new Mac" or "replace the drive"... which- the former- will prove to be THE fan remedy spun if too much SWAP ends up making the SSD fail in Silicon Macs before owners are ready to replace those Macs. At least the Fusion drives are generally replaceable in old Macs. Now, when any part fails, you have to buy a new Mac.

Lastly, open up EVERYTHING you tend to do when you feel you are taxing the existing Mac the hardest and check your RAM usage. Whatever that number is, round up and add some A.I. fudge too. That could be a fast way to a pretty good estimate based on your own actual RAM usage.

In short, while Apple beancounters are basically robbing Apple customers with far overpriced RAM (and SSD) relative to market, take best shot at estimating 2029 and then ROUND UP. If you have to own a Mac (because you cannot bring yourself to go PC instead where tremendous competition for commodities like RAM & SSD keep those prices "at market"), pay wayyyyyyyyy up from the only Store that can provide Mac RAM and you should be fine in 2029.

 

[CaptainBlue]

Lastly, open up EVERYTHING you tend to do when you feel you are taxing the existing Mac the hardest and check your RAM usage. Whatever that number is, round up and add some A.I. fudge too. That could be a fast way to a pretty good estimate based on your own actual RAM usage.

I'm currently using 39GB of RAM with the system just ticking over...

 

[HobeSoundDarryl]

So by my math you maybe add 16GB for 2029 Apple A.I. to estimate 55GB and round up to at least 64GB.

And I'm not confident at all you'll get that in a M4 iMac... so you probably should be thinking "separates" and probably Mac Studio or maybe MBpro (to be used in clamshell mode as a desktop unit most of the time). I was a long-term iMac 27" user too but went separates and am quite happy with the decision- particularly because I could go much bigger for a monitor than "only" 27", which is especially helpful for video editing. If interested, I went with the Dell 40" 5K2K ultra-wide and could never go back to 27" or so (nearly square) now, which would also rule out ASD. All that added screen width is incredibly useful for your kinds of tasks.

And, more importantly, when the Mac guts conk or the corp opts to make them obsolete, the iMac "throw baby out with the bathwater" is no longer in play. The monitor will move on to the NEXT computer.

There are ongoing rumors of an iMac Pro, but I'd expect that to be priced like the "separates" combo of Mac Studio and a good display.

Most rumors put the next Mac Studio as a Spring/WWDC release, so if M4 is dominating the thinking, it looks like the short-term path to that would be MBpro in clamshell as soon as a few weeks from now. I doubt a new M4 Mac Mini will come with 64GB+ options but we'll see. Maybe Mac Mini PRO will offer such upgrades: 16/32/64 (though I would guess more likely something like 16/32/48 or maybe 12/24/48. I'm personally doubtful about a 64GB BTO M4 Mac Mini. There IS 16/32 now with the M2 PRO version, so it's at least plausible an M4 could perhaps add on a 48-64GB BTO option.

New advice is "stand by" until the Mac event to see what Apple reveals and then make best decision thereafter.

One more option: using bootcamp, convert the computer you already have to Windows (costing you towards nothing) and find a suitable app to stand in for FCPX for the video editing. The other stuff runs just fine in Windows and you have a very powerful computer to continue being a PC for at least a few more years. When you need a dose of Mac something, can always boot into macOS too. You have the LAST generation Mac that can natively run both. There's little to stop you from switching and not having to spend more than maybe a hundred or two/three for Windows 11 and a great video editing app.

 

[CaptainBlue]

And I'm not confident at all you'll get that in a M4 iMac... so you probably should be thinking "separates" and probably Mac Studio

...

New advice is "stand by" until the Mac event to see what Apple reveals and then make best decision thereafter.

Probably right on both counts.

 

[wilberforce]

I currently use a 27" 2020 iMac with 3.8 GHz 8-Core Intel Core i7, AMD Radeon Pro 5500 XT 8 GB, and 128 GB 2667 MHz DDR4 RAM.

When/if the M4 iMacs are released in November, if they're like the present iteration of the 24" iMac, the maximum RAM would be 24 GB.

So would that be enough? I'm an Old School iMac user right back and you always whacked as much RAM in as possible with third party - i.e. cheaper - memory.

Other than the 'normal' Office work, I also use Lightroom and occasionally Photoshop for my photography, plus I also do some video editing occasionally using Final Cut Pro.

As a LR and PS user on both Intel and Apple Silicon, I can can confirm, like many others, that Adobe apps want to use more RAM (about double) on AS than on Intel machines. Reason is that they use a large portion of the unified (shared) RAM on AS for the graphical acceleration function, which previously was provided by the separate GPU's VRAM on an Intel machine. I suggest look in Activity Monitor and see how much memory is actually typically used by LR and PS on your Intel machine, and double it, for how much these apps would like to have available on AS.

I uses words like "want" and "like" rather than need. The question "would that be enough" is actually the wrong question, because it implies the answer is a black and white yes or no. A more appropriate question would be: "Will there be a benefit in having more RAM (than 24GB)?" Depending on your usage there may be a benefit, perhaps only occasionally, perhaps often. The benefit is increased speed - how much increased speed depends on your usage, and how important that increased speed is depends on you.

Fore reference I have 32GB RAM on my Intel iMac and for my LR and PS usage I feel that is plenty. I have 16GB RAM on my Apple Silicon machine and I wish I had 32GB (or more) - I frequently have large (more than 10GB) swap files using LR or PS. It functions fine, but could be faster with more RAM.

 

[CaptainBlue]

Fore reference I have 32GB RAM on my Intel iMac and for my LR and PS usage I feel that is plenty. I have 16GB RAM on my Apple Silicon machine and I wish I had 32GB (or more) - I frequently have large (more than 10GB) swap files using LR or PS. It functions fine, but could be faster with more RAM.

That answers my question: the answer is 'no' then if the maximum configuration is 24GB on the iMac. It looks like a Mac mini or Studio would be my option.

 

[HobeSoundDarryl]

...or MBpro MAX with lots of RAM and maybe a dock like the Brydge one to make it "feel" like a desktop Mac when used that way. I suspect the fastest path to any M4 Mac with probably 64GB or more of RAM is going to be MBpro MAX... UNLESS Apple surprises all with a new Studio (and probably Pro) too at the same event.

 

[Adora]

I currently use a 27" 2020 iMac with 3.8 GHz 8-Core Intel Core i7, AMD Radeon Pro 5500 XT 8 GB, and 128 GB 2667 MHz DDR4 RAM.

When/if the M4 iMacs are released in November, if they're like the present iteration of the 24" iMac, the maximum RAM would be 24 GB.

So would that be enough? I'm an Old School iMac user right back and you always whacked as much RAM in as possible with third party - i.e. cheaper - memory.

Other than the 'normal' Office work, I also use Lightroom and occasionally Photoshop for my photography, plus I also do some video editing occasionally using Final Cut Pro.

I put 64GB in my 5K iMac from 2015 for the same reason, just because it was so much cheaper and even kept the 2x4GB lying around for nothing. I think 8GB might even be enough for me in that time.

Now I have an M3 with 24GB and I only do basic things. Sometimes I think a little bit more would be good when I look at the Activity Monitor. Maybe it's the beta and alpha testing of almost anything I use, that's not a standard use-case.

Is it sure the M4 won't support more RAM than the M3? I planned to buy one as a second display for more intensive tasks and have a substitute at the same time for the case one might get damaged suddenly anytime.

They could just make it a little bit thicker to have enough cooling for an M4 Pro.

Is it even certain that they won't skip again to M5?


I'm no so into RAM speeds. Promoted is always the thousands of MHz it supports. And when I look for other things there are always several numbers I don't really understand when I want to compare it to the speed of swapping to a blazing fast flash storage. How much roughly is the difference for the stuff Apple is using at the moment?

 

[HobeSoundDarryl]

Nothing is sure about M4 until Apple releases them.

The only clue that is tangible is the M4 in an iPad which appears to have 12GB of RAM with only 6GB made available to that iPad. That has created rumor logic that the steps up from 8GB (base)/16GB/24GB might become 12GB (base)/24GB/36GB but other rumors imply the new base will hop to 16GB, thus the rumor logic of 16GB/32GB and either 48GB or maybe a jump on to 64GB.

Until Apple pulls back the curtain, it's ALL guesses about M4 Macs.

And no, what is painted on top of a chip could also change to anything at Apples discretion. We assume M4 chips are next but Apple could make them N1s or MacA or anything else if they like... including hopping on to M5 or M50. It's just a painted number. There is some chip advancement underpinning the naming scheme but Apple could arbitrarily rebrand at any time, such as OSX to macOS.

 

[Chuckeee]

When/if the M4 iMacs are released in November, if they're like the present iteration of the 24" iMac, the maximum RAM would be 24 GB.

Apple likes commonality. So if the rumor for the new M4 Mac mini is a base RAM of 16GB and an option of 32GB. I would suspect the M4 iMac will have those same RAM configurations (instead of the current 8, 16, 24GB RAM configurations)

 

[neo_cs193p]

Even 16GB would be enough for the use cases you describe. But you'll probably be able to get 32GB with the M4 iMac.

 

[ignatius345]

I currently use a 27" 2020 iMac with 3.8 GHz 8-Core Intel Core i7, AMD Radeon Pro 5500 XT 8 GB, and 128 GB 2667 MHz DDR4 RAM.

When/if the M4 iMacs are released in November, if they're like the present iteration of the 24" iMac, the maximum RAM would be 24 GB.

So would that be enough? I'm an Old School iMac user right back and you always whacked as much RAM in as possible with third party - i.e. cheaper - memory.

Other than the 'normal' Office work, I also use Lightroom and occasionally Photoshop for my photography, plus I also do some video editing occasionally using Final Cut Pro.

I'm doing more or less the same level of work as that -- Illustrator, InDesign, Photoshop, plus assorted productivity software -- on an M1 iMac with 16 GB of RAM (the most available on this machine) and it does really well with that workload.

Maybe you have a really big Lightroom database or work with tons of Photoshop layers, but even this several generation old iMac is definitely keeping its head well above water. Based on that, I would assume an M3 or M4 Mac with 24GB would absolutely fly.

 

[bradman83]

Reason is that they use a large portion of the unified (shared) RAM on AS for the graphical acceleration function, which previously was provided by the separate GPU's VRAM on an Intel machine.

There's a bit more nuance to unified memory on AS than this statement I just wanted to point out. Specifically, data can either exist in a single memory location and be worked on by the CPU and GPU at once (referred to as a "shared" memory resource), or the data can be duplicated, worked on separately by the CPU and GPU, and synchronized back together (referred to as a "managed" resource). The managed resource will indeed use significantly more memory while the GPU is doing its work, whereas the shared resource will not. It's entirely up to the developer which resource storage model they want to implement. Adobe chose the managed model, likely for either performance or compatibility reasons.

So yes, for Adobe apps their managed resources can cause RAM usage to appear higher, but the same is not true for other apps, it will depend entirely on how they're coded.

 

[Ben J.]

When the time comes, get 16, 24, or 32 if you can, and you'll be fine. Do you need to run many memory-hungry apps simultaneously? No? Just quit a couple of them, to free up ram. The quitting and launching of apps is so fast on modern macs.

My most memory-consuming app these days is Lightroom Classic with a ca 12GB catalog, and I can easily run things like Pro Tools along side it.

It is quite fantastic what the modern macs can do with little memory, but it's a very good feeling to know you don't have to worry about it because you're well covered.

You certainly won't need 128!
More is not better. You can put in a zillionGBs and it won't make a better computer.

 

[wilberforce]

There's a bit more nuance to unified memory on AS than this statement I just wanted to point out. Specifically, data can either exist in a single memory location and be worked on by the CPU and GPU at once (referred to as a "shared" memory resource), or the data can be duplicated, worked on separately by the CPU and GPU, and synchronized back together (referred to as a "managed" resource). The managed resource will indeed use significantly more memory while the GPU is doing its work, whereas the shared resource will not. It's entirely up to the developer which resource storage model they want to implement. Adobe chose the managed model, likely for either performance or compatibility reasons.

So yes, for Adobe apps their managed resources can cause RAM usage to appear higher, but the same is not true for other apps, it will depend entirely on how they're coded.

Yes it is specifically for (most?) Adobe apps. Interestingly, for PS and LR there is the option to disable graphics acceleration, whereupon RAM usage comes down to similar levels as on an Intel machine. However, then the graphics becomes choppy and laggy, and annoying to use

 

[Adora]

@bradman83 @wilberforce

I can even enable GPU for the very minimalistic UI of Adguard VPN.

I am seeing this option in more and more apps that doesn't have anything to do with photo or video.

What is the (dis)advantage of this? Does this need more RAM?

Does it help when the CPU load is on its limits? Is it generally faster than just using the CPU and recommended if I almost never do GPU intensive stuff?

It's always disabled by default when I see it anywhere.

There is also this WebGPU option in Firefox. I activated it now to see if anything changes.

 

[bradman83]

@bradman83 @wilberforce

I can even enable GPU for the very minimalistic UI of Adguard VPN.

I am seeing this option in more and more apps that doesn't have anything to do with photo or video.

What is the (dis)advantage of this? Does this need more RAM?

Does it help when the CPU load is on its limits? Is it generally faster than just using the CPU and recommended if I almost never do GPU intensive stuff?

It's always disabled by default when I see it anywhere.
View attachment 2416379
There is also this WebGPU option in Firefox. I activated it now to see if anything changes.

View attachment 2416383

I'm not overly familiar with the WebGPU API but there's an entire Wikipedia article about it and what it does here:

WebGPU - Wikipedia

en.wikipedia.org

As for other, non-graphics related apps providing hardware acceleration toggles, it's going to depend mainly on the app. Adgard VPN is a cross platform app with what looks like a custom, non-OS-native UI so it could have some performance jerkiness on lower end systems (especially on the Windows side) so bringing in the GPU to render the UI can help with that. GPUs can also help accelerate non-graphics tasks including machine learning, AI, and similar tasks that run better on that type of hardware.

As I said in my original post, whether it takes more RAM or not depends entirely on whether the resources being used by the GPU are keyed as being shared (no impact to RAM) or managed (possible impact to RAM). Short of looking at Activity Monitor and seeing if there's a difference in RAM usage with the option enabled and disabled there really isn't a way to tell. Keep in mind that a managed resource will only take up more RAM while the GPU is being used. Adgard is a VPN so I'm assuming you just let it run in the background and don't keep the window open. Since it says it's using the GPU just for UI rendering, if there's no onscreen UI being rendered then the GPU wouldn't be getting used.

It's worth noting most apps that use standard macOS UI-elements are already GPU accelerated by the system as needed, we just don't see the toggle to turn it on and off.