Is 24GB RAM overkill?

Discussion in 'Mac Pro' started by sboerup, Aug 23, 2010.

  1. sboerup macrumors 6502

    Mar 8, 2009
    So now that my MP is now finally getting ready to ship, time to buy the RAM. My needs and uses are the following:
    -LOTS of LR3 usage
    -Some regular PS CS5 use
    -regular InDesign and Illustrator use, with some Dreamweaver
    -occasional gaming
    -I normally have 8-12 apps running (ftp, twitter, quickbooks, cs5, lr3, dreamweaver, indesign, illustrator, itunes, ical, addressbook, etc)

    I have been using a 2008 MP with 16GB of RAM and been very happy. Now, I consider myself a power user, but, I never really check and see how much RAM I'm actually using. I rarely experience any slowdowns, but do still get occasional beachballs . . . less than 10 seconds so it doesn't drive me crazy. I do have an Intel 160GB SSD as my boot, my Home folder is on a separate (albeit slower 7200rpm drive), and all my media data are on separate WD Black drives with a 300GB Velociraptor for my LR Catalogs.

    I was originally only planning on getting 12GB due to the triple channel, but it's been proven that it doesn't really make any noticeable real world difference when going to 16GB and dual channel . . . but reading some stats on digilloyds and OWC benchmarks, it does show that a sizeable increase in speed when using 24GB of RAM for PS use and other apps . . .

    Now my question is, is this real world speed difference something I should jump for? My mind will always be telling me "should have gone for the 24GB", considering the difference between 16GB and 24GB is about $340 or so . . .

    Should I go 24GB or is even 16GB still overkill?
  2. Hellhammer Moderator


    Staff Member

    Dec 10, 2008
    Get 2x8GB and add 3rd 8GB module in future if needed
  3. mattmower macrumors member


    Aug 12, 2010
    Berkshire, UK
    Why guess?

    Run activity monitor and watch your paging activity and, in particular, the "Pages Out" value. If you've got all your apps running and that's relative stable you're probably okay. If that value is sky-rocketing then you might well do to add RAM.

  4. sboerup thread starter macrumors 6502

    Mar 8, 2009
    This was my original thought, but everyone keeps saying the 8GB sticks are very finicky and that it's best to buy them in the groups you plan on using . . . if that makes sense. Not so much the money issue I guess, but, just rationalizing the extra expense when I could add another 120GB OWC SSD for the price difference.
  5. sboerup thread starter macrumors 6502

    Mar 8, 2009
    I do occasionally watch it, also have the iStats dashboard widget running. Normally I'll have 8-10GB memory as "inactive", normally 4GB at most as "active" . . . where do I check the "pages out" amount?
  6. Hellhammer Moderator


    Staff Member

    Dec 10, 2008
    I haven't heard that. I know you have to use the same modules though so if you buy from OWC, then you have to buy the 3rd module from OWC. I would actually contact them and ask is it needed to buy them at the same time or is it fine to add the 3rd module later on
  7. ghostchild macrumors 6502


    Jun 17, 2007
    i got 24gb ram to do the same work you do with yours on my new MP a little overkill i think but a little bit more future proof i think yes. 32gb in the future for me when I get into video again.
  8. sboerup thread starter macrumors 6502

    Mar 8, 2009

    OK, loaded up the applications that I would use during a heavy session . . . I can't really interpret it the best, I know what the Free/wired/active/inactive/used means, but not so much on the next column.

    I'm thinking like ghostchild, 24GB will definitely be more than I probably need but it will also future-proof my needs if I ever get into video work. And I'd rather spend $340 extra now than try and sell my 16GB (4x4gb) later and get 24GB.
  9. js81 macrumors 65816


    Dec 31, 2008
    Inactive memory is not being used, you so really don't even need 16GB (though if I were getting a MP it would have AT LEAST 12GB or so).

    Also, you can add Page Ins/Outs to the iStat widget - I have it on mine. Click the "i" to get to Settings, go the "Sections" tab, and change Memory to "Advanced."

    Attached Files:

  10. mattmower macrumors member


    Aug 12, 2010
    Berkshire, UK
    Maybe someone expert in how the VM works can chime in and correct me but my understanding is this:

    The important figure is "pages out".

    "VM size" is related to the amount of virtual memory all your processes have requests and isn't relevant. It may be many multiples of the size of your actual memory. Mine is currently 244GB on my 4GB machine. You'll note iStat doesn't even bother to report it.

    "pages in" is pages the VM copies from memory to the swap file. This happens routinely and is not important to performance.

    "pages out" is pages the VM is reading from the swap file into memory. This is bad. It means the process is blocked until the page comes off the disk. Even an SSD is going to be slow here compared to the pages already being in main memory.

    In my experience, the way the OS seems to organise its affairs, some paging seems to inevitable even if you never exhaust your memory completely. So small numbers here shouldn't be a cause for concern.

    If your "pages out" figure either remains stable or grows slowly over a working day it means that your applications are running without swapping and you have enough memory.

    If "pages out" spikes and rises rapidly as you're working it means you've got memory pressure and the system is swapping consistently as different processes try to run.

    Hope this might be helpful.

  11. peskaa macrumors 68020


    Mar 13, 2008
    London, UK
    You're hardly touching that 16GB of RAM you have installed currently - Page Outs of 8MB for your entire uptime (whatever that was) is minimal at best. That huge chunk of 10GB inactive RAM is just sitting there waiting to be used. Even if you go the video route in the future, you're not going to be pushing it hard enough to use all that.

    Long and short, for your uses, even considering future video use, 24GB is a waste of money. Plus when you're editing video you can, y'know, close PS and LR...
  12. sboerup thread starter macrumors 6502

    Mar 8, 2009
    This is what I've always assumed, I was never really using even half of my 16GB RAM. Will save some money and just stick with 16GB.
  13. Honumaui macrumors 6502a

    Apr 18, 2008
    one thought on LR
    24 gigs is fine more the better I say using SL and 64 bit especially for PS use !
    you can get away with 16 ? either one but if you can swing it stick it in now and be happy !

    depending on how you work in LR ? but putting the cache on a SSD can help out

    I might post my full findings ? but here is the quick

    your original files dont matter to much
    your catalog ? not a big deal on a SSD its a touch quicker but I did not test for heavy meta data writing etc.. as that is done on import and not messed with again ? my test was more for Develop module to get the white sliders white so I could get working :)

    my mac is a 3,1 2.8 8 core with 14 gigs
    SL in 64 bit and running latest RC of LR 3.2 RC or whatever it is ?

    so in dev mode going from image to image you can see how moving the cache to the SSD is the most important

    Attached Files:

  14. oncilla macrumors newbie

    Jun 23, 2007
    probably overkill

    I have freelanced at several shops using maya and after effects and have never ever seen that much ram installed. 12-16gb seems to be the ideal situation, and I am always happy with that setup. Anything less than 8gb is painfully brutal though.

    I ordered the Hex and am leaning towards 2x8gb sticks to future proof things though. Never know what future versions of stuff might need...
  15. Honumaui macrumors 6502a

    Apr 18, 2008
    I have never used Maya ? but I make a living with PS and LR

    I have 14 gigs and need more I am taxed all the time on memory !!!!!

    PS in 64 can use the memory so if you can swing it get it I say :)
  16. mabaker macrumors 65816


    Jan 19, 2008
    sboerup, would you be so kind and post a screen shot of your RAM usage out of the Activity monitor AFTER working some hours on the programs you mentioned?

    The screen shot doesn’t say much unless it#s taken after some hours of sometimes extensive work flows.

    It’d be very interesting to me to say at least cuzz I am one of few convinced ppl that ever since Snow Leopard got launched Apple screwed Mac OS X’ dynamic pager and the paging out is flawed since then.
  17. dknightd macrumors 6502

    Mar 7, 2004
    I'm no expert, but I like to see 0 page outs. If this is really the OPs typical workload I'd add 8 gigs to what you have now. 16 + 8 = 24.
    On the other hand you have lots of unused memory - you can reclaim much of that by closing programs not currently in use. Work your machine the way you actually use it, if you frequently page out get more memory - if you only page out in a worse case situation, you are probably fine. Since programs and files keep growing, I'd get more memory than you think you need (or at least allow for expansion)
  18. sboerup thread starter macrumors 6502

    Mar 8, 2009
    After debating in my head, I went ahead with 16GB (2x8gb) . . . this way I'm somewhat future-proofing myself in case I want to order more later. Anyone have any reason why this wouldn't work?

    $298 each from
  19. dknightd macrumors 6502

    Mar 7, 2004
    I just learning about how these new mac pros work (I'm still not sure what
    happens if you add a 4th dimm - does it go to single or dual channel - and how much does that really matter)

    That said, I think your solution is a good one. For awhile at least you should be able to pick up the matching dimm. Wait too long, no problem, the price will drop and you can replace them all :)

    disclaimer: 3x4 met my needs, is a little cheaper than what you bought, and might be faster.
  20. deconstruct60 macrumors 604

    Mar 10, 2009
    If it is the benchmarks I'm thinking of then the increases are when the benchmarks include "huge" files. If you don't load huge files then won't see as dramatic effect. Pragmatically, what that "huge" benchmark is doing is forcing Photoshop into using the scratch area as "swap space" because the data gets so large it won't fit into memory anymore. At that point Photoshop starts pushing/pulling subsets of data in and out. The 24GB threshold turns that off again because it does fit.

    In other words it is not measuring memory at that point but disk for machines with limited RAM. What happens when have machines that are under that threshold then really comparing two different sources of bottlenecks.
  21. Honumaui macrumors 6502a

    Apr 18, 2008
    this should answer the 3 vs 4 memory for ya :)
  22. barefeats macrumors 65816


    Jul 6, 2000
    I tested the 3.33GHz 6-core with two different memory configs. Then I ran a 64 bit memory stress test.

    4x8G = 32G = 10.5 GB/s
    3x8G = 24G = 14.3 GB/s (or 36% faster)

    However, when I ran After Effects CS5 project render using 12 cores and 1.5G per core, the 32G config took 72 sec, the 24G took 71 sec. In other words, if there is a difference in real world performance, you would need a stopwatch to detect it.

    Why? Because few if any real world apps use the full memory bandwidth. I'm still testing. If I find any app that benefits from the 3 stick "triple channel" config, I'll report it here.
  23. xgman macrumors 601


    Aug 6, 2007
    You can never have enough money or enough ram. :D
  24. milo macrumors 604

    Sep 23, 2003
    I'd be careful about buying two 8 gig sticks. They are very finicky and there's a chance that if you buy more in the future they might not be compatible, even if they list the same specs. They might be fine but personally I wouldn't take such an expensive risk.

    Not to mention that it's probably cheaper to buy 4x4 for now and just replace them later (and sell them or trade them in if you can) when the price of 8s comes way down.

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