Is M4 MBA enough to replace 2020 27” iMac?

[voicycle]

My desktop is a 2020 i7 27” iMac with 40GB RAM (I bought 8gb base and added a single 32gb to the other slot). It powers a second display plus there’s a smaller third one in my voice recording booth, but that’s just a mirror of the main (or sometimes of the secondary depending what I’m doing).

The most demanding work it does is voiceover recording with a live link to a remote studio, so the sound recording requirements are never that intense (max 5 tracks and a dozen plugins), but I do notice hooking up multiple webcams and doing videoconferencing alongside a recording session can get the fans going.

I have no issue with this machine right now so am not trying to replace it immediately, but if it died tomorrow I would probably replace with a Mac mini and studio display.

My issue is with my travel machine (which I would never plan to use for audio recording). It’s basically just an email, browser, and MS Office machine so portability is most important. Last year my beloved 2015 12” MacBook finally got so slow that I had to replace it so I went for a M4 iPad Pro with keyboard case. It’s perfectly capable and I’m constantly learning how to use it more efficiently, but after 6 months I’m still really missing laptop functionality, particularly when I’m at home and just want to work in another room.

So now I’m wondering if M4 has finally brought us to the point that even a MacBook Air will outperform my iMac (in a fanless package no less!) Docked for audio but with full freedom to go elsewhere too, even if that’s only to the sofa (since iPad does cover my travel needs pretty well).

Obviously the processor is there, and I know ARM Macs require less RAM than intel for the same performance, but by how much? Would I need 24gb to match what I have? 32gb? Would MBA cooling limitations be enough to require a MBP for this use case? And am I right to assume that M4 MBA is limited to 2 UNIQUE external displays but could easily mirror one of them to a third?

(I think the alternative is to look for a good price on a refurbed or secondhand M3 Air at/near base spec and then revisit the whole 2 computer vs 1+ dock situation in a couple years when the intel iMac is more noticeably behind the times)

 

[theorist9]

1) While swap might work better on an AS Mac than your Intel Mac (because the former has a faster SSD), it's still suboptimal to have insufficient RAM. I.e., unless there have been big changes to an app in porting it from x86 to Apple Silicon, that somehow significantly reduce RAM requirements (this is unlikley), you will need just as much RAM to run the app optimally on an AS device as on an Intel Mac.

So the best way to estimate how much RAM you will need on an AS device is to determine how much RAM you're using on your iMac.

This can be tricky to determine from the various memory usage numbers in Activity Monitor. The best way to determine if your work needs more than a certain amount of RAM is to install that amount of RAM in your iMac, use your most memory-demanding workflow, and see whether your memory pressure (shown at lower L) stays green. Alas, given the memory sticks you have, the only RAM amounts you can test are 8 GB, 32 GB, and 40 GB. E.g., you'd need 8+8 to test 16 GB, and 8+16 (or 3 x 8) to test 24 GB.

2) This may not apply to your setup, but an M4 Air wouldn't replace a 27" Intel iMac if your work requires three full-sized (≈27") monitors, since the M4 Air can drive only two. The M3 Air is further limited because it can drive two only when in clamshell mode.

 

[russell_314]

My desktop is a 2020 i7 27” iMac with 40GB RAM (I bought 8gb base and added a single 32gb to the other slot). It powers a second display plus there’s a smaller third one in my voice recording booth, but that’s just a mirror of the main (or sometimes of the secondary depending what I’m doing).

The most demanding work it does is voiceover recording with a live link to a remote studio, so the sound recording requirements are never that intense (max 5 tracks and a dozen plugins), but I do notice hooking up multiple webcams and doing videoconferencing alongside a recording session can get the fans going.

I have no issue with this machine right now so am not trying to replace it immediately, but if it died tomorrow I would probably replace with a Mac mini and studio display.

My issue is with my travel machine (which I would never plan to use for audio recording). It’s basically just an email, browser, and MS Office machine so portability is most important. Last year my beloved 2015 12” MacBook finally got so slow that I had to replace it so I went for a M4 iPad Pro with keyboard case. It’s perfectly capable and I’m constantly learning how to use it more efficiently, but after 6 months I’m still really missing laptop functionality, particularly when I’m at home and just want to work in another room.

So now I’m wondering if M4 has finally brought us to the point that even a MacBook Air will outperform my iMac (in a fanless package no less!) Docked for audio but with full freedom to go elsewhere too, even if that’s only to the sofa (since iPad does cover my travel needs pretty well).

Obviously the processor is there, and I know ARM Macs require less RAM than intel for the same performance, but by how much? Would I need 24gb to match what I have? 32gb? Would MBA cooling limitations be enough to require a MBP for this use case? And am I right to assume that M4 MBA is limited to 2 UNIQUE external displays but could easily mirror one of them to a third?

(I think the alternative is to look for a good price on a refurbed or secondhand M3 Air at/near base spec and then revisit the whole 2 computer vs 1+ dock situation in a couple years when the intel iMac is more noticeably behind the times)

I am pretty sure the M4 will outperform your old i7 iMac. If you’re doing long sustained task, probably 15 minutes plus that max out the CPU it’s possible you could have some throttle with the MacBook Air. Is what you’re doing going to max out the CPU? I don’t know so maybe ask someone that specifically uses whatever software you use? If it does, you might be better with getting a Mac mini if you ever decide to upgrade from your iMac.


Questions I would be asking is will the software and whatever specialized hardware accessories you’re using work with Apple Silicon? I don’t know anything about voice recording, but I would make sure whatever you have will work.

I’ve never been one to like the concept of plugging in a laptop to use as a desktop then unplugging it to take it with me. I’ve done it for work, but that wasn’t my choice. That’s just me and my thoughts, but I know a lot of people seem to like the practice

 

[mr_roboto]

A M4 Air will be faster, by a margin which might surprise you. Here's a comparison of the M3 Air to the 2020 27" i7 iMac you own:

https://browser.geekbench.com/v6/cpu/compare/10897074?baseline=10890973

Geekbench deliberately avoids measuring thermally throttled performance on fanless systems by idling a few moments between each test. However, the M3 is so much faster that I'd be willing to bet it beats a 2020 iMac even when fully throttled. M4 Airs should be faster again.

Besides, your workload doesn't sound like the kind which will ever force an Air to throttle. Late model Intel iMacs are notorious for spinning their fans up at anything beyond a light load. If the only thing that you do which gets them going is videoconferencing, you'll be fine. Apple Silicon has better low-energy accelerator hardware for videoconferencing than Intel iMacs did, so most videoconferencing apps stress the system way less than you're used to on Intel Macs.

Obviously the processor is there, and I know ARM Macs require less RAM than intel for the same performance,

FYI, this idea is a myth.

The way to think about RAM and performance is that more RAM doesn't add performance, instead it's more like having too little RAM for the things you're trying to do puts you in a penalty box. When your computer runs out of RAM, macOS has to start swapping data that'd ordinarily reside only in RAM to and from the disk. Since disks (even SSDs) are much slower than RAM, this can hurt performance a lot.

The one real advantage Apple Silicon Macs have in this department is that their faster SSDs make light swapping much more tolerable. However, if you can afford enough RAM to not swap at all, or at least limit it to a very rare event, you still want to do that. You're wasting the performance potential of that amazing CPU by making it pause and wait for the disk all the time.

All that said, I don't think you have high requirements here, either. I suspect you'd do fine on 24GB or better. Maybe even 16, but I don't want to guess low and thereby give you bad advice.

And am I right to assume that M4 MBA is limited to 2 UNIQUE external displays but could easily mirror one of them to a third?

Unfortunately, it doesn't work that way. You get two external displays, and that's it. You can't cheat a third by mirroring one of the other two.

If running three external displays is a hard requirement, there is no way to get that in anything short of a Max chip (whether it's M1, M2, M3, or M4). On the other hand, from your description, I'm not sure you really need that? Sounds like the third display is purely to mirror one display to your recording booth, where I presume you can't directly view the big displays. If so, you could just bring the whole MBA into the booth (why not, no fan equals zero noise), dock it directly to the booth's display, and let everything outside the booth be dark.

(I think the alternative is to look for a good price on a refurbed or secondhand M3 Air at/near base spec and then revisit the whole 2 computer vs 1+ dock situation in a couple years when the intel iMac is more noticeably behind the times)

Trust me, when you get an Apple Silicon Air you're going to realize the iMac is already very noticeably behind the times. I had a 2019 i9 iMac when I bought my 2020 M1 MBA, and was pleasantly shocked to find that for most purposes the M1 was faster (and not by a small margin). The gap's even bigger now. Used to be true that you could find some very compute intensive tasks that high end Intel iMacs were faster at, but that's getting harder and harder.

My advice is to buy a 24GB or better Air (M3 or M4, doesn't matter) to replace your failed MacBook, since you definitely want to do that, and start experimenting with doing your iMac tasks on it. If it works out, you can pick up the monitors and so forth that you'll need to have it truly replace the iMac.

 

[FreakinEurekan]

I know ARM Macs require less RAM than intel for the same performance

This is something of a fallacy. Yes, ARM will outperform Intel even with less RAM - but that's more a function of HOW MUCH faster ARM is than Intel, not how "Efficient" it is.

Of course, on the other hand - you might not NEED 40GB of RAM. The trouble is, of course, you can't just "pop in more" like you did with your iMac so you need to ensure you get "enough."

I'd take a look at Activity Monitor Memory page during heavy workload... not the Memory Pressure or total RAM used per se (though if Memory Pressure is yellow/red... you have your answer!) but more at what's being used by your top apps. "Total" memory usage is misleading because macOS will grab any available RAM for cacheing, whether it needs it or not, which makes memory usage look higher than it really needs to be. But if you're using, say, 20GB just for your recording software... 16GB is gonna swap a lot, 24GB is probably also too small. But if it's more like 8GB then yeah, you can probably get away with a lot less.

 

[voicycle]

Thanks all, this is really helpful, though it does raise almost as many new questions as it answers. Tips on how exactly to assess RAM usage were particularly useful. I’ve not had a chance to monitor things whilst tracking during a video call yet, but just by loading a few different recording sessions I can see I’m barely taxing the RAM at all with ProTools. I do want to leave a lot of headroom for that to change since I’m learning to work more effectively with a bigger suite of plugins just now, and also to be prepared if I ever need to work on something a bit more longform than the stuff I’m currently doing, but just now I’m looking at mostly sessions that run on less than 1Gb of RAM 😂

Here are the other key things I learned:

• In the few instances I demoed I maxed at 27Gb systemwide RAM usage without even bothering to close unused apps (including a bunch of browser tabs on Chrome which I’ve tried to migrate away from for RAM reasons but just never got up to speed with the workflow of Safari so ended up switching back). That doesn’t include any video call demo so it’s just a first look and I’m sure could go higher, but it seems like a new 24Gb system would be plenty to leave headroom for future growth.
• Biggest surprise was a big memory leak and CPU load from some crash reporting daemons that seem to always fire up when I use a Webcam Effects app that I got for the sole purpose of being able to digitally zoom the inbuilt camera on the iMac. I’m guessing this is actually the bulk of what gets the fans spinning during video calls and that it’s due to a buggy app rather than any genuine resource requirement. That’s something that’s easily solved with any new Center Stage equipped camera (or even just with a comparatively modest third-party webcam purchase on the existing setup).
• Dropbox turns out to be the standout RAM hog of all the apps that are functioning correctly - it will hold more space in RAM than the sum total of all the data I have in Dropbox, and google suggests this is a fairly common occurrence. Thankfully not a big enough percentage of my 40Gb to be an issue, but a good prompt to move away from that app entirely soon (I’m using Synology Drive to keep a consistent shared file system across all devices these days so Dropbox is mostly a legacy product for me now.) I did end up updating Dropbox to the new Files API in the meantime and saw an instant drop in RAM usage so will keep an eye on it over the next little while.

And am I right to assume that M4 MBA is limited to 2 UNIQUE external displays but could easily mirror one of them to a third?

Unfortunately, it doesn't work that way. You get two external displays, and that's it. You can't cheat a third by mirroring one of the other two.

That’s a shame, though you’re right that I don’t need exactly the three displays I have. I do need two at my desk for a different strand of my work, but the laptop screen would be perfectly adequate as my secondary. Currently it’s a 32” 4k display that has an Apple TV hooked up to one of its other HDMI ports, so I couldn’t just get rid of it since it has another use, but I could make it redundant when I need a screen in the booth.

If you connect more displays to a MBA than it supports do you still have the ability to see them all in display settings and then just choose on a case by case basis which ones you want to use and which one to sideline, or would I actually need some kind of hardware switch for that? (I initially wrote KVM but I think these days it’s just an HDMI switch or similar - showing my age there 😂)

Questions I would be asking is will the software and whatever specialized hardware accessories you’re using work with Apple Silicon? I don’t know anything about voice recording, but I would make sure whatever you have will work.

All good on this front but thanks for flagging!

I’ve never been one to like the concept of plugging in a laptop to use as a desktop then unplugging it to take it with me. I’ve done it for work, but that wasn’t my choice. That’s just me and my thoughts, but I know a lot of people seem to like the practice

This is a good point and I think ultimately I probably would prefer to have a Mac mini AND a laptop, but I guess this was me trying to see if I could justify the spend on a laptop purchase right now by also using it to replace my desktop (and likely selling the iMac to recoup some cost). Sounds like it’s certainly possible but it just won’t really be optimal. So I probably need to do something closer to the following:

My advice is to buy a 24GB or better Air (M3 or M4, doesn't matter) to replace your failed MacBook, since you definitely want to do that, and start experimenting with doing your iMac tasks on it. If it works out, you can pick up the monitors and so forth that you'll need to have it truly replace the iMac.

This is where the bigger questions start to come up I think - if I go down that route and then end up paying studio display money to replace the iMac with a MBA, why wouldn’t I just stick with it for an extra 6-12 months until I could justify the cost of the studio display plus a Mac mini to maintain that as a complete system? And if I’m doing that then do I even need to spec the MBA to be able to handle anything remotely demanding?

Also got thinking about the fact that if I’m keeping the iPad Pro for travel and portability and a MBA is primarily a household device, then maybe I should be looking at 15” instead of 13” which is a whole different rabbit hole to go down. No idea when I last picked up at 15” MBA so I probably need to wander into an Apple Store and at least see what I think of the form factor in the flesh…

Lots to think about. Mostly I’m just really grateful to have a much clearer understanding of RAM requirements and what ARM does and doesn’t offer in comparison to what I know already.

 

[throAU]

Any m series mac with sufficient ram will handle that workload without breaking a sweat.

I’m not sure where the “apple silicon Macs require less ram” tripe comes from. But it’s bs. Probably from Apple superfans trying to defend Apple being super stingy with memory or misunderstanding why Apple silicon was so much faster than Intel.

Buy as much ram as you think you’d need on Intel. GPU needs to share the ram as well.

 

[russell_314]

I’m not sure where the “apple silicon Macs require less ram” tripe comes from.

Likely due to the extremely fast storage and processor that’s able to swap out better and suffer less slow down. Running out of RAM on an Intel Mac mini is going to cause you more pain than if it was on an Apple Silicon mini.

This being said all you have to do is check the memory pressure. If you’re in green with 32 GB on Intel, then you’re fine with 32 GB on AS. If your current machine is in yellow, then it’s probably a sign you need to upgrade. Don’t go by how much RAM is used because macOS will take what you give it.

Of course, if you have bottomless pockets, then there’s no point in even worrying about this. Just buy the maximum spec on everything because there is no downside. Maybe slightly more power usage, but I doubt if that it would even be noticeable.

 

[voicycle]

Thanks for all your help on this. I made a purchase but I think I'm going to go back this weekend and change form factor, so the process is still ongoing. Here's where I landed so far:

• Even though MBA probably could replace my current iMac, it really is preferable to have desktop and laptop machines separate. And the bulk of the desktop expense right now would really be replacing the 27" 5k display in the iMac rather than replacing the computer itself, so I might as well hold off a while longer and make my current purchase laptop-focused rather than trying to make it be everything all at once. By the time I get round to spending Studio Display money (or even a lower budget alternative), I probably won't actually have to stretch that much to include an appropriately spec'ed Mac Mini alongside it.
• So, if MBA is to be a laptop first and foremost there's no need to max its spec to try to match the iMac. It would be good to push beyond base spec though as that means it probably can still do 99% of everything I use the iMac for in a pinch.
• If MBA is an at-home laptop and I'm still relying on iPad plus keyboard case for travel (where it's mostly an email machine anyway), then might as well see what the 15" is like.

So I bought 15" 24/512gb and have had it a week and a half. Right from the start I found the ergonomics of the larger form factor problematic (specifically wrist position when typing whilst reclining on a sofa). I've been sticking with it to try to see if it's just something I need to get used to or if it really is the wrong size and shape for my use case. Jury's still out.

But my 14 day return period is up on Monday so I'm thinking I'm going to go back and swap it for the 13" with otherwise identical spec. Then I've got another two weeks to see if I miss the bigger machine at all. I hope I don't because it's a lot of extra admin to swap laptops multiple times!

Related question: setup the 13" from a Time Machine backup of the 15" or as a fresh computer? I did the 15" as a fresh setup which wasn't awful, but if there's nothing additional I'd gain by going through that whole process again then I'd rather take the shortcut this time.

 

[chrono1081]

Absolutely it is, anyone saying otherwise never tried. I am a HEAVY computer user and had an 16 inch MBP Intel i9, 64 gigs ram, whatever the top graphics card was...

...and my M2 MacBook Air with 16 gigs of ram and whatever the top graphics card option is blew it out of the water, it wasn't even close.

Too many people are hung up on RAM but the new chips are so efficient you can get away with a lot less RAM and not even notice it. I ran programs like Houdini, Blender, Unity, Final Cut, Motion, Xcode, Affinity Suite, etc all perfectly fine on my M2 Air.