Is there not much difference between 8gb and 16gb for MBP retina?

Discussion in 'MacBook Pro' started by galaksy, Apr 19, 2014.

  1. galaksy macrumors 6502

    Apr 19, 2014
    I read somewhere that there isn't much of a difference between 8gb or 16 RAM for a MBP retina because it uses SSD.
  2. SandboxGeneral Moderator emeritus


    Sep 8, 2010
    RAM and a storage drive are two different things. The RAM will help keep a computer running multiple apps at the same time be more smooth. The SSD will help read/write times and the decrease the load time of launching apps.

    If you use many apps at once, and/or memory intensive apps, then more RAM is a good idea.
  3. davidjearly macrumors 68020


    Sep 21, 2006
    Glasgow, Scotland
    The only way we can help advise on how much memory you need is for you list your computing needs.

    In general, 8GB will be more than enough memory for the majority of the consumer population in the latest rMBP.
  4. MartinAppleGuy macrumors 68020


    Sep 27, 2013
    You are right. When you run out of RAM, your MacBook will swap some contents of RAM to disk. If the disk (backing storage) is an SSD, it is much less noticeable when this occurs than when using a HDD.

    Bellow is a little reply I done yesterday to someone to help then understand how RAM works in OSX and how 8Gb of RAM is more than enough for 99% of users:

    When having iMovie open with a large video, and Chrome with a 5-10 tabs, I am using 6Gb of my 8Gb of RAM. The system can then use another 2Gb before it hits the total, where is will start to clear App Cache, then another 2-3Gb (App Cache) before it starts compressing RAM, then another 4-6Gb before touching Swap (ie- ran out of RAM). So in this circumstance, using 6Gb of RAM is using 31.5% before I run out of RAM.

    If your RAM pressure is red and you are a Swap/Page-out larger than a few Kb then your Macbook has ran out of RAM. If it is green, and you still have a lot of cache left, you are using a tiny amount.

    With RAM compression, I had all of my applications open, iMovie doing some exporting, and 100 tabs split between Chrome and Safari (around 50/50 each) and I was using 15.14Gb of RAM with my 8Gb of RAM iMac . And it still never touched swap. And my RAM compression was green. This is due to the heavy caching OSX does (to make apps launch instantly, rather than fetching data from backing storage which is a much slower process) as well as RAM compression. RAM compression uses the WKdm compression algorithm allowing data held in RAM to be compressed and decompressed almost instantly meaning you can have a lot more running before you run out of RAM. As said above, I use using 15.15Gb of RAM (and my iMac has 8Gb). What this means, is that the data within RAM consisted of 15.14Gb (with some being compressed to make it fit on the 2X4Gb modules, but then instantly decompressed when needed).

    Another thing to note, is that when I was using this much, my iMac was still very responsive (90% as responsive when compared to not pushing it). RAM pressure was also green, meaning I could push around 17Gb of RAM on my 8Gb system.

    I hope this has helped you understand how RAM works in Mavericks. When you see "Memory Used: 7.xx", don't just think you are using all of it. Look at App Cache then add that number on to your total RAM (i.e 7.xx out of 10/11Gb of RAM used, rather than 7.xx out of 8Gb used), then look at Compressed RAM and if 0 add 6Gb again on to your total. In the end, you are using 7Gb out of 17Gb. Also look at RAM pressure: green indicated you have loads of free RAM, amber indicated you are pushing the system RAM but there is still RAM free, and red indicated you have ran out of RAM and data has to be swapped to disk.
  5. galaksy thread starter macrumors 6502

    Apr 19, 2014
    Could it be because you are using an iMac and for MBP retina it might be not as efficient?
  6. dusk007 macrumors 68040


    Dec 5, 2009
    No there is no difference between the hardware. RAM usuage only depends on what you are software you are running. An iMac handles it no different than a notebook.

    The only difference is that on a notebook swapping also hurts battery life a little even if the performance isn't such a problem with an SSD. Which is why RAM compression is well worth it, which didn't exist before Mavericks. Usually in the use cases that you get to with serious swapping happening on a 8GB RAM notebook your battery life will be bad anyway because the CPU will be very busy. The bit of extra battery drain from the SSD wouldn't make a noticeable difference.
  7. MartinAppleGuy macrumors 68020


    Sep 27, 2013
    RAM wise, they are exactly the same. That is how the software works with the hardware in Mavericks. From my tests, you will only need more than 8Gb of RAM if you are using a lot of VM's.

    Here is a video of a 2010 Macbook Air with 2Gb of RAM using Mavericks. With RAM compression and App Cache, the system can use around 4Gb before it needs to swap to disk, and when it does, it is an SSD so it is not so noticeable.

    PS - I have an iMac with a HDD, and my RAM performed as I stated above. You would have a even better experience on a Macbook Pro with an SSD.
  8. magnumpi macrumors member

    Sep 24, 2012
    I'm not sure you can avoid swapping. Modern OS are designed to perma-fill up your RAM so everytime you open a file, an app, browse the web... etc something has to be removed to make room for the new data.
  9. dusk007 macrumors 68040


    Dec 5, 2009
    Sure something has to be removed to make room but it doesn't have to be swapped to disk. The OS just clears some of the non essential stuff. The OS tries to fill up RAM but it can only do so with growing file caches, keeping recent pages refreshed that could already be cleared and some other things.

    As MartinAppleGuy explained the OS can clear quite a lot until it actually gets to the data that has to be in RAM and would need to be swapped to disk if removed.
  10. galaksy thread starter macrumors 6502

    Apr 19, 2014
    Does Maverick makes Mac more RAM efficient than Windows?
  11. dusk007 macrumors 68040


    Dec 5, 2009
    No it just is better than the OS used to be.
    The thing is many apps itself just need way more memory in OSX than their Windows counterparts use. It isn't really the fault of the OS. Also Microsoft put a lot of work in to make sure Windows runs well on really cheap mobile hardware with little RAM. The hardware OSX has been selling on considers 4GB more or less the absolut minimum. OSX doesn't have to run well on tablet hardware, they have iOS for that.
    Apple just improved RAM management but it still uses as much as it did. Especially with many applications just being not optimized for RAM efficiency in OSX by their developers means OSX is never going to win in this department. With 8GB it really doesn't make a difference.
  12. MartinAppleGuy macrumors 68020


    Sep 27, 2013
    Much more efficient. RAM can be compressed in Windows, but no where near the extent of OSX. I have tried Windows XP, 7 and 8.1 and all of them paged out when reaching the RAM limit (ie 4-4Gb).
  13. NewishMacGuy macrumors 6502a


    Aug 2, 2007
    As has been stated above, your RAM needs will depend on your particular usage pattern. For the average OSX user 4GB is a little thin on the ground these days, 8GB is plenty, 16GB gives you comfortable headroom if you run a VM (like Windows) and is a good baseline if you're actually working in both OSX and your VM simultaneously, and you likely only need more than 16GB if you also need a Mac Pro.

  14. itegypt macrumors 6502


    Aug 6, 2011
    I got the 16 for later on if I want to sell it:D

  15. Intelligent macrumors 6502a


    Aug 7, 2013

    Thats a lie since SSD speed and ram is 2 totally different things. If you are doing light editing, some gaming, web browsing and emailing then 8GB won't really feel different to 16GB. However if you have open loads of applications at the same time, play resource-craving games and do more heavy editing then with 16GB you will definitely feel difference.
  16. MartinAppleGuy macrumors 68020


    Sep 27, 2013
    Your not understanding the question (or the way RAM works). When RAM is exhausted (ie full), the OS writes some of the contents of RAM to backing storage. This process is called Swap (and also known as page-out). With PCIe based flash (used in all rMBP's), this process is around 10X quicker than a HDD and is much less noticeable than then when using a HDD. An SSD is hundreds of times slower than standard 1600Mhz RAM, but a hard drive is thousands of times slower than RAM. All this means that when RAM runs out (with RAM compression, it is around 15.5Gb where RAM is full on 8Gb of RAM), the affect Swap has on the user when using an SSD is much less noticeable than when paging-out with a HDD (which is crippling).

    Hope you now understand,



    And FYI, I have done heavy video editing (2hr long 1080p video, several layers of video, several layer of audio, lots of video stabilisation, several effects and transitions) with no problem at all. I have also had every app I have on my Mac open as well as iMovie doing some rendering, a PSD open, 50 tabs in Chrome, 50 tabs in Safari, a few word docs open, a few spreadsheets (large spreadsheets), a presentation open. When I done this, RAM compression allowed me to use 15.14Gb of RAM with my 8Gb of RAM. My RAM pressure was still great, and performance was still great. I have found with all of my tests that 8Gb of RAM can be pushed with around 15.5Gb of data before swap kicks in and RAM pressure goes amber. I think I could possible push around 16Gb before it gets too heavy though.
  17. philxor macrumors regular

    Dec 21, 2010
    I'm doing some work now emulating network elements in VMs, including nested VMs, and they are very resource intensive. The difference between 8GB and 16GB is huge. Once you hit the swap, even with it being SSD, it's dog slow compared to being able to extend into the extra 8GB of RAM.
  18. Justinhub2003 macrumors regular

    Jul 17, 2012
    Cincinnati Oh
    I have a late 2013 MacBook Pro Retina (2.3ghz, 16gb, 512gb, 750m) as my personal computer and my work computer is a mid 2012 MBPr (2.3ghz, 8gb, 256, 640m).

    In day to day use I notice absolutely no difference between the 2. But then again, a lot of my daily stuff is web based and some .Ai and .PSD stuff.

    But I think in the future I will appreciate the extra ram and also when I'm running virtual machines, I am able to give my the VM 8Gb of Ram and still have 8Gb for OS X.
  19. thundersteele macrumors 68030

    Oct 19, 2011
    Many years ago (i.e. 3-4 years) it used to be that when you ran out of RAM, the computer would slow down notably, switching between Apps would be painfully slow, and e.g. opening a random file on the HDD could take several seconds or even minutes.

    Based on my own experience I feel that things have improved a lot. As already mentioned SSDs are much more responsive, so RAM content that is being swapped out to the SSD is not such a big deal anymore. I also feel that in particular with Mavericks, OSX has become much better at managing App memory, and deciding what to move to Swap or what to compress or what to remove from RAM first.

    Based on that experience I have decided to purchase a new machine with 8 GB of RAM, and I think that this is also sufficient for the current and future (~3 years) needs of most potential buyers.

    On the other hand I would not say that the SSD makes more RAM completely unnecessary. For those who have very RAM intensive work flows (e.g. using several virtual machines), more RAM will be better. Those people usually also know about their RAM needs ;)
    Therefore the rule of thumb is: If you don't know whether you need more than 8 GB, you probably don't.
  20. TechZeke macrumors 68020


    Jul 29, 2012
    Rialto, CA

    Can we please get a RAM sticky thread now?

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