If you’ve been thinking about buying an ARM-based Apple device, you must’ve heard of Unified Memory.
It sounds fancy, there’s no doubt about it, but what is it exactly, and how much of it do you really need?
Understanding its peculiar (and most impressive) nature is of the utmost importance as it is, in part, what makes Apple’s latest and greatest devices so darn powerful (and devilishly fast, too).
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There’s a fair bit of ground to cover, so let’s get down to the nitty-gritty!
What’s Unified Memory?
Apple’s M1 and M2 chipsets (and, presumably, their successors) are all tightly integrated. Unlike traditional x86 computers, these SoCs (System-on-a-Chip) contain most key components underneath the same hood.
This kind of design has allowed Apple to create a unified memory architecture which, in turn, allows both the CPU and GPU to access the same pool of memory.
This is similar to a regular iGPU set-up but only on the surface level — Apple’s UMA (Unified Memory Architecture) is much more advanced than it might seem at first glance.
Moreover, it is vastly different from what we’ve all become accustomed to over in the x86 world — an architecture that, while undoubtedly sufficient, isn’t nearly as avant-garde as what Apple has to offer.
Why Is Unified Memory So Fast?
In a standard, Windows-based PC, your CPU communicates directly with your Random Access Memory (or RAM, for short).
Dedicated graphics cards have their own pool of dedicated memory — VRAM — the amount of which tends to vary wildly based on the model you have and its intended use-case.
The only “issue,” however, is that it still takes time for these pools of memory to be accessed by your processor and graphics card (and other components, too). They might be in relatively close proximity, but there’s still a limit in regard to the speed at which they can be accessed.
Now, by no means is this limit debilitating, but it exists nonetheless.
The faster your components can communicate and transfer data, the faster your device will perform and execute whichever task you might throw its way.
How Does Apple’s Unified Memory Work?
Unlike regular motherboards and RAM sockets which use a system of wires (typically called a bus) to communicate and transmit data, unified memory relies on an interposer substrate (a layer of silicon, in other words) for the same task — hence the much faster performance.
The RAM part within Apple’s SoCs isn’t literally a part of the chipset but is rather connected through the same substrate.
It’s also as close to the SoC as possible (right beside it, in fact) — another huge difference whose benefits should not be underestimated as it allows for all kinds of data to transfer at a much greater speed.
Max Tech did a neat test comparing Laptops based on Unified and regular RAM in this video that shows their performance difference in RAM-heavy workloads:
Unified Memory — Biggest Drawbacks
Apple’s UMA, for all its many strengths and benefits, sure isn’t without a long laundry list of drawbacks and limitations. Let’s take a closer look:
Deceptively fast — This might sound like a plus, but it can very easily become negative. Once you’ve used up all of your available memory, your Mac device will immediately (and without hesitation) resort to swap memory. The OS itself will still feel (fairly) responsive and snappy, but if this becomes a habit it could, by all means, do a number on your SSD further down the road.
It cannot be upgraded — This, one could argue, is the biggest and most debilitating problem. On a regular desktop PCs, if you need more RAM, all you need to do is buy another stick or, at worst, swap out your existing memory for a brand-new kit. On an ARM-based Mac device, however, the amount of unified memory cannot be changed no matter what you try. This, for laptops, is somewhat acceptable — it’s no different in the world of thin-and-light Windows ultrabooks. The Mac Studio (and Mac Mini, for that matter), is a machine that’ll stand on your desk for the years to come. Not being able to upgrade any component whatsoever can, by all means, be deemed a dealbreaker. Now, granted, the machine itself is so darn powerful that, odds are, you won’t need to upgrade anything further down the line, but the point stands nonetheless.
Extremely expensive — Want to double your unified memory? You’ll have to shell out an additional $200. Labeling this as an obscene premium would be an understatement.
How Much Unified Memory Do You Need? That depends on what you plan on doing with your ARM-based Mac device. If it’s just light web browsing, standard productivity work, and perhaps a bit of photo or video editing on the side then you’ll get by with 8GB — but barely so. Apple’s latest SoCs rely a lot on swap memory which, in the long run, may end up shortening the life span of your internal SSD. The more RAM you have, the less often your Mac will have to resort to this measure. That’s the thing: having 8GB of unified memory feels a lot faster than it should precisely because of Apple’s engineering wizardry, and while that’s a stellar benefit for all potential buyers, it is nonetheless attained through relatively extreme means — i.e. a staggering overreliance on swap memory usage. Having 16GB of unified memory, therefore, is pretty much the sweet spot for most demanding users. That’s still not an incredible amount of memory, but it’ll nonetheless suffice for both light and heavy workloads alike. Just keep in mind that there’s no way to upgrade the amount of unified memory on your device, so think twice before making any kind of purchasing decision. 8GB might be a bit too close for comfort so, if you can, make sure to go with 16GB if you’ll be using your device for the years to come and have the tendency to multitask. Unified Memory recommendations for specific Workloads We’ve written an overview guide of how much RAM you need for different workloads here, but while those numbers are great for x86-based machines using actual RAM, with unified memory we have to keep in mind that the GPU also wants its share of memory. So here’s how much unified memory we recommend for different workloads: Workload / TaskMinimum Unified Memory RequirementRecommended Unified Memory AmountBasic Everyday Use4-8GB16GBVideo Editing8-16GB64GBGraphic Design8-16GB32GBMotion Design8-16GB64GB3D Modeling8-16GB32GB3D Rendering8-16GB64GBCAD8-16GB64GBMusic Production8GB64GBProgramming4GB16GBGaming8-12GB32GBStreaming8GB16GBVR16GB32GB How Much Unified Memory Can My Apple Device Have? That depends on the SoC. Here’s a simplified overview of each chipset in Apple’s line-up (at the time of this writing) and the maximum amount of unified memory that it can support: ChipsetMaximum Amount of Unified MemoryM1Up to 16GBM1 ProUp to 32GBM1 MaxUp to 64GBM1 UltraUp to 128GBM2Up to 24GB Just keep in mind that each upgrade — on Apple’s official website — will set you back an additional $200. And, no matter your chipset of choice, you won’t be able to upgrade anything further down the line so think twice before making any kind of purchasing decision. Conclusion Apple’s unified memory is, in short, an astonishing achievement. There’s really no other way to say it. Still, it is a bespoke solution, one that comes with quite a long list of drawbacks and limitations — to say nothing of a steep asking price. The way it harnesses swap memory is also fascinating — an 8GB Mac device really does feel a lot faster and more capable than one would ever expect. You shouldn’t, however, let that fool you: eight gigabytes are still eight gigabytes, and no amount of software- or hardware-based wizardry will ever change that.
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