I have only 8gb of RAM on my iMac. I wonder if I should upgrade. Using iStat Menu I see that the Ram is used around 50% most of the time and gets up to 80% when doing more intensive stuff (e. g. audio rendering). Does this mean my RAM is still not needed to its potential or does the system keep 20% free as a reserve and would like to use more if I‘d get more?
I would say the simple rule is; if you can afford it, buy as much as you can afford. The more water you have in the swimming pool the easier it is too afloat and the more friends can join you!, So the more RAM the smooth apps run and the more you can have running at once.
When I buy a new computer RAM is the most important to upgrade, then choose SSD if the standard model has normal mechanical drive.
18months ago I got a 27" 2017 iMac that came with 8Gb RAM. I was surprised at how usable it was with that little RAM, however my usual practice of using RAM-hungry Chrome with multiple tabs (I currently have 14 tabs open in two Chrome windows) definitely hit the OS hard, especially if I tried running other apps simultaneously (as I do). I bought 32Gb RAM in the form of two Crucial 16Gb sticks (currently around $160 for the upgrade) to give me 40Gb total, installed in about two minutes, and I haven’t looked back.
First priority is SSD. If you already have that, then upgrade your RAM. Sounds like it’s not something you HAVE to do right now, but might be helpful in the future.
RAM is a simple install 2-minute install on older (and current 27") iMac, and it’s an Apple-approved user-install. Hard drive/SSD installs are much more difficult and may necessitate removing the screen with suction cups, among other things - and can void your warranty. So I’d disagree with the idea that the ‘first’ priority is cracking open an iMac to install a SSD. You’ll see a big speed-up with more RAM if you use multiple apps (or multiple browser tabs)
You can get an equivalent boost to an internal SSD if you use an external-case SSD connected by Thunderbolt. But I wouldn’t place that option above RAM unless I was accessing a lot of big RAW or video files (in which case I’d want the RAM too).
Before I decide if I spend the money (which I will certainly do, if it has a positive effect) I would like to understand the numbers iStat is giving me. Would the system use more RAM if it had more available? Because the existing 8 GB never get used up, the system could squeeze more out of it. So I wonder if I even hit a point where more than 8 make any difference. (Using the analogy with the pool: Are my friends sitting in one corner of that pool anyway and would they even notice if it were bigger in the other corner?)
By ‘not getting used up’ macOS is swapping your data to disk then intelligently retrieving them and reasserting them into RAM when needed.
Data writes and reads to disk slows your Mac. When kept in (much faster) RAM, your system runs faster.
So you could get away with 8Gb RAM for a long time, but you’d have a substantially slower experience if you used multiple apps and windows and tabs in daily use. John Siracusa discussed gave a good overview of swapped/compressed RAM here:
Ah, okay! So the amount of compressed RAM shows me how much more RAM the system would like to have?
No matter how much of it that you have, RAM should almost always be nearly 100% in use after any appreciable period of time. At the very least, the system should be using “unused” RAM to buffer file I/O.
If you’re seeing swap use going up and the system is slowing down, then that’s a sign that your system would make use of more RAM. If you don’t already have an SSD, then that may be the better upgrade, but that depends on a few other factors.
Two things are generally true for computers: You can’t have storage that’s too fast, and you can’t have too much RAM
Ah, Swap has some huge peaks. I´ll get more! I have the fusion drive. I know a pure SSD would be even better, but it´s a decent compromise for me.
My personal experience is with an MBP 13 with 8GB RAM and a more powerful MBP 15 with 16GB.
I upgraded because of RAM, but it’s quite specific why. I still use the 13 for work use and have zero issues; for my general Keynote/Chrome/Numbers work with 1-2 apps at a time it is 100% ok.
In fact, for Xcode, Final Cut and Logic it is 100% ok IF I only use one app at a time.
For my hobby though I want to have multiple ‘pro’ apps open and for this the memory in the 15” is invaluable.
The difference is noticeable in that I don’t get screen flickering, pauses and general weirdness when switching apps.
My advice is, if you want to upgrade you’ll notice some difference.
If you’re hesitant and not noticing obvious signs that your computer is struggling, you don’t actually need 16GB.
I have 24GB installed on my Late 2015 iMac and it is pretty slow at times. I have about 35-40% of free hard drive space available. I’m guessing my issue is the fusion drive instead of an SSD. My Macbook Pro is so much faster, with only 8GB of ram and a similar set up apps/dev tools installed. I know this doesn’t help you out that much with your decision. I’m sure my computer got faster when I installed the ram, but not enough IMO.
That hard drive absolutely. I’d recommend SSD at this point. You will witness huge spike in speed after SSD.
Is SSD installation easy with Late 2015 iMac? I was looking into maybe selling it and getting a new one, but all the base models still have fusion drive unless I pay $2000+
It’s a pain, regardless of which iMac.
Better to get an external Thunderbolt SSD. You csn even make that your boot drive and you’ll see faster overall system performance.
I wasn’t sure if that was an option, but that sounds like a decent way to go!
TB3 has a max speed of 40Gbps. The internal drives Apple use are very fast, 3Gbps. But in ordinary usage you’ll simply notice that it’s overall faster than your Fusion drive, and it’s simple to use and much cheaper than in the past. (1Tb external Samsung T5 drive under $200, 500Gb for under $100).
If you’re considering buying an SSD and tossing it into a TB3 case you can save a few dollars, but you’ll need to research cases and their controllers etc.
Also, you might find useful this article from BareFeats.
I believe @bowline beat me to this one
Okay, I did it and it was so easy. Let’s see how the performance changes.
I hated working with an external drive when I had my Macbook and the fusion drive with its luxurious 3TB was a big relieve for me (even though I don’t need that much, but I wanted to be sure to have enough). I don’t know the benchmarks, but I guess, this is a fine compromise. I’m gonna stick with this machine for a while and I’m glad it has the fusion drive at least, should be much better than a normal hdd.