How much RAM is useful?

Discussion in 'iMac' started by 2ms, Mar 25, 2016.

  1. 2ms macrumors 6502

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    Nov 22, 2002
    #1
    I see the benchmarks that OWC does that show large performance gains on things like creating 50 GB images in Photoshop.

    Can anyone tell me how much more RAM improves (or doesn't) performance on more common tasks such as web browsing, Office, basic Photoshop on typical image files (rather than 50 GB ones). Would I see performance improvements across the board on just mundane tasks if I was to upgrade from 8 GB to 16 GB or more?

    At the moment, Activity Monitor shows my memory use at about 5 GB. I wonder whether or not if I had more RAM headroom OS X would take advantage of it by shifting more items into memory (e.g., if I had 16 GB to capitalize upon OS X would be utilizing 9 GB or something rather than the current 5).
     
  2. mildocjr macrumors 65816

    #2
    8 GB of RAM is more than enough for any of those tasks. Depending on how large your photoshop docs get depends on if you need more.

    As far as how RAM works:
    Your computer loads everything you see and all the tasks that run constantly into RAM. This includes the many programs that run in your menu bar.

    Active/Wired - What OS X uses
    Used - What everything else uses
    Free - What hasn't been used
    Compressed - What has been squished down to provide more space for other things

    OS X uses about 1.2 - 1.4 on a cold boot just on its own. When you open up safari the webpage content is added into RAM, when you leave the webpage, the content is flushed from RAM (basically allows for other data to overwrite it)

    4 GB is good for Surfing, watching movies, playing music, etc..
    8GB is good for Games, basic photoshop/illustrator, full lightroom

    Once you start getting upwards of 7 GB on a Mac it's time to look at 16 GB.
    16 GB is good for everything
    32 GB is good for having every application on your mac opened at the same time.
    64 GB+ is a waste of money for consumer devices at the time of this post.

    Think of RAM as your desk at work. Your desk holds so much stuff, when you start working on something you move something to your desk, when you no longer need it you might leave it out in case you come back to it sooner than you think you will, after it has been out there for a while you think I need to get rid of this and you put it back where it belongs. RAM works a lot like this in conjunction with your processor and disk drive.

    Ultimately with you at 5 GB I wouldn't worry about a RAM upgrade, you are probably facing bottlenecks from other parts of your computer, either a slow hard drive (unless it's flash storage) or a slow processor.
     
  3. trifid, Mar 25, 2016
    Last edited: Mar 25, 2016

    trifid macrumors 65816

    trifid

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    May 10, 2011
    #3
    Not that great for browsing and multiple windows/tabs... each tab can be like 100-300mb each, I mean it's usable, but the more ram, the less hiccups you'll get even in something simple like a browser.
     
  4. G4DPII macrumors regular

    G4DPII

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  5. mildocjr macrumors 65816

    #5
    Trifid, I know you are a power user who has multiple tabs open, for my daughter who is a high school student and watches Netflix all day with facebook and email opened in other tabs, she has no problem with 4 GB she also doesn't have a ton of apps open on her MBA.

    In the requirements of 2ms's discussion he is debating on going with 16 GB but he still has 3 GB free out of his 8 GB (I apologize if I assume your gender wrong) and is using Photoshop in this instance. With Photoshop open and 3 GB free, I can safely assume that he has some pretty large Photoshop projects and may have mail, safari with a few tabs, and iTunes opened at the same time, maybe an instance or two of Finder windows.

    I am looking at this discussion as if money does not grow on trees and trying to ensure that 2ms can be as profitable as possible with the outcome of this solution.

    To add to my previous bit, I do know that MS Office is a memory hog on Macs and could be a reason for your RAM being eaten up. I personally just stick with the default mail app (unless I need HTML signatures) and install iWork apps instead. They are much better on memory management but I understand if it is not compatible with your environment.

    Also, if you are looking for moderate performance gains (1/4 second gains) and money for RAM is no object then 16 would be the way to go for Photoshop, 32 for 3d rendering.

    If you are looking for a big performance gain ( 3/4 - 2 second gains) then you will be looking at a processor.

    Disk speed is only relevant when you are looking for OS startup and app launch performance.
     
  6. trifid, Mar 25, 2016
    Last edited: Mar 25, 2016

    trifid macrumors 65816

    trifid

    Joined:
    May 10, 2011
    #6
    I'm sure some users can work fine with 4gb today, though it's very possible that may not work so well in the near future, judging from previous history, OSX gets quite increasingly ram hungry. But please lets clarify, the multiple-tab usage is not reserved for power users: students, shoppers, anyone trying to do any research, it's not uncommon to open many tabs/windows as you research/browse, so it's not just power users that benefit from extra ram.

    This is ram usage right now from my mac, just from 6-8 tabs or so in Safari:
    [​IMG]
     
  7. Weaselboy Moderator

    Weaselboy

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    California
    #7
    For this usage pattern you are very unlikely to see any improvement at all going from 8 to 16GB. See this test.
     
  8. CausticPuppy macrumors 65816

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    May 1, 2012
    #8
    8GB is enough for just about any normal computer usage including photo editing, movie editing, etc.

    If you're running Windows VM's you might want 16GB.

    I just got a new (refurb) 27" iMac 5K with the base 8GB and have another 16GB on the way, so I'll have 24GB. More than I need, but RAM is cheap (if you add it yourself).
     
  9. Ursadorable macrumors 6502

    Ursadorable

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    #9
    For me, I tend to use a 4GB RAM drive for my browser cache so I don't unnecessarily put strain on my SSD boot drive. But then again, I tend to leave my computer on all the time.
     
  10. iMi macrumors 6502a

    iMi

    Joined:
    Sep 13, 2014
    #10
    Just as a reference, I have the iMac with 3.4Ghz Core i5 and 16GB of RAM and with about 20 applications open right now, including Fusion running windows 10, plus word, excel, two email clients and a bunch of safari windows, plus Steam and a few PDFs, I am showing 4.62GB of RAM still free.

    16GB is plenty for most people.

    On the other hand, I constantly run out of free RAM on the latest Macbook Air with 4GB. It's simply insufficient for most of the basic activities. In fact, I'm looking to upgrade now. It's just annoying and becomes noticeably bugged down.

    Hope this helps.
     
  11. cube macrumors G5

    Joined:
    May 10, 2004
    #11
    8GiB is the basic.

    16GiB is not enough for everything, but is very good for most. That shortcoming, and the small SSD is why I returned the top rMBP.
     
  12. Isamilis macrumors 6502

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    Apr 3, 2012
    #12
    IMO, SSD or fusion drive has much more impact to the performance compared to RAM.
     
  13. mildocjr macrumors 65816

    #13
    Not entirely true. Data that is read from disk is much slower than RAM, but lack of RAM is what forces the data to be read from disk.

    It's best compared to baseball. The pitcher, batter, catcher trio is your processor. The batter on deck (all the gear on waiting for the current batter to finish) is your RAM, and the players in the dugout is your SSD or HDD.

    The pitcher batter and catcher determine how fast the game is played (CPU speed determines how fast the data is read from the L1, L2, and L3 cache).

    The batter on deck is available for play as soon as the home plate is ready for him. (This is where the data in RAM is pulled from RAM and sent across the front-side bus to the processor's L3 cache which is then sent to the L2 cache, and eventually L1 cache.)

    Think of the L3 cache as the batter walking up to the plate, the L2 cache is the batter at ready stance, and the L1 cache is the ball being tossed, the processors actions on the data are the same as the batter swinging the bat and either hitting or missing the ball.

    Finally you have the players in the dugout that aren't in use now but can be when needed. This is essentially the data on your hard disk.

    Relating all of that to your statement, If the next batter called is not the batter on deck (RAM), they are called from the dugout (disk) where they have to put on their gear, grab their bat and start walking up to the plate (L3 cache) while bypassing the batter on deck.

    It takes a lot longer for the batter to come from the dugout than from on deck as you can understand so your statement is true in the occurrence that your RAM is completely full and you rely on the speed of your disk drive to get data ready for the processor. If RAM is available the most common bits of data will be loaded at application start so it's snappy. If your application requires data that has not been loaded into RAM and it's relatively small (6 MB mp3 for example) it will almost instantly be loaded (cached is more appropriate) into RAM and will start playing as soon as the first bit of data is moved into the processor. Now all of this happens at the speed of your processor. A bit being 1 or a zero 6 MB is ~6 million bytes, or 48 million bits. if you have a 1.4 Ghz processor it can process 1.4 Billion bits a second, so 6 MB would be loaded in about 0.034 seconds. Pretty quick. If it has to load from disk and the RAM is full, you are still looking at a pretty quick load time but it may take a second or two to start playing. Now imagine when you have 100 different things going on that might be 100+ Mb in size. This is where the problem occurs.

    TL;DR
    Your hard drive is slow but RAM is there to make things snappy, running out of RAM means you're no longer snappy.

    I know this is lengthy but I like to explain things out in hopes that it answers other questions and educates along the way.
     
  14. jerwin macrumors 65816

    Joined:
    Jun 13, 2015
    #14
    I rarely use gigs 16-24.

    This is typical,

    Screen Shot 5.png

    Lots of Cached files, no memory compression.
    The most memory intensive application in my experience seems to be preview. Load up a few hundred pages of some illuminated manuscript, and preview's allotment can soar to 2-3gb.

    But even with a couple of memory hogs running, 16 gb would still be enough to be comfortable.
     
  15. mildocjr macrumors 65816

    #15
    Here's an update of mine, I upgraded to 32 GB of RAM because I needed it for VMs, but you can see a typical (small) Logic Pro project that is 67 MB in size uses a lot of extra stuff. The project takes about 8 seconds to load off a HDD due to all of the plug-ins, audio files, and midi files that it has to load.
    Screen Shot 2016-04-20 at 11.29.06 PM.png
    I include a few more columns that I find helpful but the big thing to note is even though my project is only 67 MB in size, I read roughly 500 MB of data from disk in plugins (such as equalizers and instruments), audio samples, automation data, and midi files. My plugins all use the same part of memory but where they might vary in their controls will exist in different parts of RAM (leads to the 8 second copy to memory time). Purgeable memory is memory that is not currently in use and marked for overwrite.

    My wired memory is what my RAM uses for all system functions to keep the OS up and running, the App memory is stuff that was kicked off by the system or myself to do stuff, iStat menus runs as a daemon so that wouldn't be something I ran but it's still App memory, the Application itself is something I chose to run at startup so I own it and it adds to memory.

    I'm no where near my 32 GB limit, but I've hit the 16 GB limit on some of my larger projects, another reason why I upgraded to 32 GB.

    Like I said 8 GB of RAM is usually plenty for basic photoshop because those layers add up. Lightroom is a walk in the park in comparison. If you find yourself getting close then you should upgrade to 16 GB. At this usage, I wouldn't even consider going past 16 GB which is my next logical step past 8 GB.

    You don't want to mix RAM sizes say to make 12 GB in my case, although 12 GB will boost performance if you are hitting 8 GB, it will degrade system performance from what you'd get with 16 GB.

    Another thing to consider which has a far less impact is using the memory bank channels properly. Never put an odd number of RAM sticks in your computer (the exception being 1 stick of RAM). If you look at where your RAM goes (say you have 4 slots like on the back of an iMac) you will see numbers listed, most of the time the order is something like 1, 3, 2, 4. This is based on dual channel memory, 1 and 2 is where your first two sticks go, 3 and 4 is where the last two sticks go. If you are going for 8 GB of memory you might use 4 GB x2 in slots 1 and 2, but if you had 4 sticks of 2 GB in all 4 slots, you'd get a slightly higher performance boost. For 16 GB you'd use 4 x 4GB and for 32 GB you should use 4 x 8 GB.

    RAM should be incremented as 1, 2 ,4 ,8 ,16, 32, 64*, 128* (*Mac Pros or when iMacs can handle it).
    You can also increment at 3, 6, 12, 24, 48*, 72*, but you'll run into minor performance issues. (Some computers ship with these numbers so it's not a huge loss and average users probably won't notice).
     
  16. maflynn Moderator

    maflynn

    Staff Member

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    Boston
    #16
    That might have been the case 15 years ago but not today. The OP will be wasting money if he boosts his ram to 32GB for no reason other then he can afford it.
     
  17. chukronos macrumors 6502

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    Oct 20, 2004
    Location:
    Colleyville, TX
    #17
    Old thread, I know. But, I just increased my RAM from 8 to 24GB. It is like I have a new computer. I was getting frustrated with the speed of my iMac - spinning ball, etc. I always have a ton of web pages open. Now, it is back to running like it is brand new. I wonder if photoshop was using a lot more resources than I though.
     
  18. off_piste macrumors 6502a

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    Oct 25, 2015
    #18
    I went from 4 to 32 and it's been awesome. I'm usually at 13gb used without even opening photoshop so I'm happy I spent the extra $65 bucks or so for something I'll use for years.
     
  19. trifid macrumors 65816

    trifid

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    May 10, 2011
    #19
    Nice deal, Apple charges $600 for 32gb on the iMac :rolleyes:
     
  20. phrehdd, Apr 24, 2016
    Last edited: Apr 25, 2016

    phrehdd macrumors 68040

    phrehdd

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    Oct 25, 2008
    #20
    Simple to understand and missed by many. In days of yore, applications would want to take a certain amount of space within memory and that pretty much was it. Today, some apps (and OS) are smart enough to take as much real estate in RAM as they can within certain parameters. You could run 3 apps with 4 gigs of RAM and they would run. You could run the same 3 apps with 8 gigs and they run and so on. The question then becomes which applications benefit from more RAM and can you tell the difference.

    A nice example is that I have two applications open and app memory is saying - 7.28 gigabytes used. These are email and Firefox browser. On a system with less RAM, both would work and less RAM would be used. However, given certain circumstances within the browser, I will get better performance with more RAM.

    Photoshop - there are settings within Photoshop which deals with RAM and scratch space. Depending on how you use Photoshop, and how you set your settings would determine a great deal about the performance of Photoshop. If someone tells you that 4 gigs is enough, then either they are referring to jpeg editing or don't have full information (my way of saying they don't have a clue) on optimizing hardware for Photoshop.

    I think most folks do fine with 8 gigs of RAM for general use including very light Photoshop. If you are getting into larger files, then you really do need to consider tweaking the settings, opting for decent scratch space (SSD ideally), increasing RAM to 16 gigs AND understanding that the amount of history levels when left large can slow down Photoshop (also addressable in settings).

    In short, you really can't have too much RAM but you can certainly feel the pain of too little RAM. - Especially on many Apple products that do not offer the option for the owner of the Mac to increase RAM after purchase.
     
  21. Dubadai macrumors regular

    Dubadai

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    Location:
    Stockholm, Sweden.
    #21
    I had 8GB for almost the first year of owning my iMac, and just accepted some of the speed when doing lots of photo editing in Photoshop and Lightroom. Then I found a good deal on 16GB RAM, so went and installed that along with the standard 8GB. Man, was there a difference. Especially when having many photos at once opened in Photoshop.

    I'd say get 16! Depending on what you do of course. 8GB for basic stuff and web is enough of course!
     
  22. T-Will macrumors 6502a

    T-Will

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    #22
    I'm going with 16GB to future-proof my purchase.
     
  23. chukronos macrumors 6502

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    Colleyville, TX
    #23
    lol! My iMac just did the 3 beeps. I tested the new ram and it was no good. Oh well. Time to set up an exchange.
     
  24. MacStu09 macrumors regular

    Joined:
    Aug 27, 2009
    #24
    Ram is cheap, (as long as you don't buy from apple, lol). Just be safe and go with 16gb.

    The question of how much is useful is completely dependent on the user. For me 16-32gb is very useful; as I had numerous beachballs and hangs for up to 5-10 minutes with only 8gb.

    With only google chrome open, I generally use about 8gb. Granted, I usually keep numerous tabs open - but while using even just preview and excel on top of that, I easily hit over 12-13gb. Just spend the $35-60, depending on where you buy it. It's easily worth it.

    8gb should be a bare minimum for any modern system.
     
  25. h9826790 macrumors 604

    h9826790

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    Hong Kong
    #25
    I think you have to check the memory usage in your activity monitor. Anyway, I have 48G RAM, and I realise the system usually stable at around 27G usage, and then use the rest as cache. Same pattern as then I only has 32G RAM. So, for my case, 32G is almost the minimum to keep everything work at full speed.

    As the others pointed out. Modern OS is very smart, they can let you run quite a few apps and the OS with only 8G of RAM, however, not in optimum performance. New OS almost always able to take advantage from more RAM. My Mac can easily utilise all 48G RAM when I am doing some 4K video editing / encoding stuff.

    Anyway, here is my general usage before and after the RAM upgrade. The system only need less than 4G for wired memory. So, this is what the OS really need, anything more than 4G is fine for the system itself. On top of that, I need another ~24G to keep all my apps running in the background. Besides that, the system will use the rest as cache. When the remaining RAM runs out, the system will start to compress the memory (as show on the upper screenshot). If more memory avail, the system will further use them as cache to speed up the system (as show on the lower screenshot).
    27.8G RAM usage.jpg 26.5 + 12.jpg So, at the moment, I believe that I hit the right spot on memory config, not too less (require memory compression, swap, etc), and not too much (not even able to use as cache).

    In your case, you have to check your usage. If memory compression / swap exist, that means your system can still benefit from more memory (however, not necessary gives you noticeable improvement. In fact, for the new iMac, the SSD is so fast, you may not even able to feel the difference if only require small amount of swap).

    If you didn't see any memory compression / swap in your activity monitor, that means most likely you can't benefit from having more memory. IMO, there is no need to buy more RAM for future proof, the RAM is user upgradable parts, and you can always buy more RAM later with lower cost. Buying too much memory now is just a waste of money.
     

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