Buying a new MacBook Air

[n1xf]

Every few years I upgrade to a new MacBook Air, and every time I consider what to buy, I wonder about how much RAM I need. Typical logic is to buy more if you use more intensive apps--which is not very crisp. Is there an app that actually tracks what apps I use and their impact on RAM so that, when I'm ready to upgrade, the app just says: buy this much RAM because....

And another thing. Say I have 8GB RAM and I'd be better off with 16GB--what does "better off" mean? The apps still run, but maybe they run slower or something. The computer runs slower when it gets hot, too. So what? If the computer will do what I ask eventually, and the only real variable is how long it will take to do it, I need a metric, like: 24% of the time your computer is processing below its optimum speed because of insufficient RAM. Or, 32% of the time your computer is processing below its optimum speed because of high temperatures.

And even more: if I get more RAM, does that reduce the time the computer throttles down because of heat? or does it make it worse because more electronics are in use?

 

[Alameda]

All of the new MacBook Air models will have a minimum of 16GB of RAM, so your decision has been made, unless you buy a close-out model.

To answer your question: Your computer has a processor with 8 or 20 (or whatever) CPU cores, and to do its work, the CPU cores read and write data from your computer’s RAM, millions or billions of times a second. As you open apps and documents and browser windows, the computer uses more RAM to hold the large data structures they create.

If you use up the available RAM with applications and documents and browser windows, the System automatically “pages” some of the RAM to storage… the very, very fast SSD drive inside your computer. Although this SSD is very, very fast, it is not as fast as the computer’s RAM. This will cause things to slow down… maybe. You see, the system operates very intelligently on this and it’s good at paging out the least likely-used data. But maybe when you Command-Tab from Photoshop to Word, there might be a 2 second delay as a gigabyte of Photoshop RAM gets written to SSD and a gig of MS Word gets read into RAM. Most likely, you won’t even notice.

Of course, it’s possible for the memory use to be so extreme that the system “thrashes” as it constantly pages from RAM to SSD, but this would be a situation where you’re WAY over-using the available RAM. And you can always just quit one of your apps, freeing up memory, and you motor right along.

 

[4sallypat]

Any of the Apple Silicon Macs have been such a wonderful transition.

I love them all - I have base: M1 Mac Studio, M2 Macbook Air, M3 MBP.

All of them perform so well - no more heating or the noisy fans like the Intel Macs used to do....

 

[n1xf]

All of the new MacBook Air models will have a minimum of 16GB of RAM, so your decision has been made, unless you buy a close-out model.

To answer your question: Your computer has a processor with 8 or 20 (or whatever) CPU cores, and to do its work, the CPU cores read and write data from your computer’s RAM, millions or billions of times a second. As you open apps and documents and browser windows, the computer uses more RAM to hold the large data structures they create.

If you use up the available RAM with applications and documents and browser windows, the System automatically “pages” some of the RAM to storage… the very, very fast SSD drive inside your computer. Although this SSD is very, very fast, it is not as fast as the computer’s RAM. This will cause things to slow down… maybe. You see, the system operates very intelligently on this and it’s good at paging out the least likely-used data. But maybe when you Command-Tab from Photoshop to Word, there might be a 2 second delay as a gigabyte of Photoshop RAM gets written to SSD and a gig of MS Word gets read into RAM. Most likely, you won’t even notice.

Of course, it’s possible for the memory use to be so extreme that the system “thrashes” as it constantly pages from RAM to SSD, but this would be a situation where you’re WAY over-using the available RAM. And you can always just quit one of your apps, freeing up memory, and you motor right along.

Thank you for your reply. I'd read something this AM about maybe getting 24GB and I wondered why do we keep guessing? The system knows how I use it. Why can't it recommend stuff? But these questions remain unanswered:
1. Is the only effect of insufficient memory that response time increases?
2. Since the computer throttles due to heat, how does that relate to overload? If the RAM is overloaded and the CPU is running hot because of the task load, and the computer slows itself down to maintain temperature, what is the my real world perceived impact?

 

[Alameda]

Thank you for your reply. I'd read something this AM about maybe getting 24GB and I wondered why do we keep guessing? The system knows how I use it. Why can't it recommend stuff? But these questions remain unanswered:
1. Is the only effect of insufficient memory that response time increases?
2. Since the computer throttles due to heat, how does that relate to overload? If the RAM is overloaded and the CPU is running hot because of the task load, and the computer slows itself down to maintain temperature, what is the my real world perceived impact?

The Mac Activity Monitor app has a display called “Memory Pressure”, which gives you and idea of whether the RAM is “overloaded.”

Memory Pressure needs to be quite high to cause the sort of effects you’re describing. You’re welcome to pay the extra $200 for a 24 GB system, and nobody knows how you use your computer except for you.

My first Mac had 1 MB of RAM, so I’m aware of keeping an eye on how many apps I’m using at a time. But these systems can manage many concurrent apps at once, and I think saturating 16 GB of RAM takes a bit of effort, unless you run several virtual machines.

 

[kschendel]

Thank you for your reply. I'd read something this AM about maybe getting 24GB and I wondered why do we keep guessing? The system knows how I use it. Why can't it recommend stuff? But these questions remain unanswered:
1. Is the only effect of insufficient memory that response time increases?
2. Since the computer throttles due to heat, how does that relate to overload? If the RAM is overloaded and the CPU is running hot because of the task load, and the computer slows itself down to maintain temperature, what is the my real world perceived impact?

1. Yes, unless you constantly drive the machine deep into page thrashing, which might possibly shorten the life of your SSD. Realistically, though, you'd get rid of the machine long before that happened, because it would be largely unusable. So yes, the only effect is response time.

2. I can't think of any real relation between RAM pressure and CPU thermals.

And, yes, you can use Activity Monitor today to get a read on your RAM usage today. The problem is that software isn't static, and usage patterns usually aren't either. Even if you run the same software (never upgrading!) with the same usage patterns, RAM usage may change. Web sites evolve and may need more RAM to render in your browser. Etc etc. It's not something easily amenable to predicting with any precision.

 

[n1xf]

Thanks. But still missing the point: why doesn't either Apple or someone else make a program that monitors the behavior of my Mac while I'm using it and come up with a recommendation about the configuration of the next Mac I'm going to buy?

 

[Alameda]

Thanks. But still missing the point: why doesn't either Apple or someone else make a program that monitors the behavior of my Mac while I'm using it and come up with a recommendation about the configuration of the next Mac I'm going to buy?

The computer can’t know what you’ll be doing in three years and how much memory those apps will take. It can show you whether you have sufficient memory right now.

I think that 16 GB is fine for most users. It’s plenty for me, and I open folders with a few hundred 45 megapixel RAW photos and scroll through the thumbnails and edit them and export them. Maybe I could make it even faster with a brand new machine and even more memory, but it’s fast enough. Whether a task takes 2 seconds or 2.5 seconds doesn’t make a difference to me. As far as I know, I’ve never run into high memory pressure using my Mac. My last Mac was an 8 GB model with Intel CPU, and when I used VMWare Fusion to run Linux at the same time as Mac, then I ran low on memory… but that’s because Fusion cut my memory in half, giving 4GB to Linux.

 

[chown33]

Thanks. But still missing the point: why doesn't either Apple or someone else make a program that monitors the behavior of my Mac while I'm using it and come up with a recommendation about the configuration of the next Mac I'm going to buy?

Maybe you could use ChatGPT or some other AI bot to summarize web results for you. You'll probably need to tell it things like your current memory usage, current apps, etc. in order to get anything like a useful response. I suspect that one of the AI conversational models might work better, because they typically maintain a context between your prompts.

If you think of the AI as basically a super summarizer that's been trained on a lot of text from a lot of websites, then answering your question mostly amounts to summarizing relevant replies from a number of web forums, and cutting out irrelevancies.

On the down side, it might be too much of a summarizer, and give you nothing but the kind of overly generalized response that is typical of AI responses when it can't glean enough detail from the prompt.

 

[kschendel]

The computer can’t know what you’ll be doing in three years and how much memory those apps will take. It can show you whether you have sufficient memory right now.

Yes, that is what I was trying to say, in a rather obscure and prolix manner.