Scratch disk/Photoshop: RAM vs. HDD

Discussion in 'Mac Pro' started by paulgl, Feb 10, 2008.

  1. macrumors newbie

    Jan 26, 2008
    I'm going to get the 20008 2.8 8-core Mac Pro w/750 gb WD as primary boot and the Samsung spinpoint 500 gb for data. I'll use the stock drive for saving backup (I'm not that concerned if I lose photos).

    For maximum photoshop speed/efficiency, is it smarter to go w/ 12 gb of RAM or 8 gb RAM and a WD 150 gb 10k RPM as a scratch disk?

    Thanks in advance!!!
  2. macrumors regular

    Jul 30, 2007
    Sussex, UK
    I applaud your patience!
  3. macrumors 603


    Oct 2, 2006
    The Land of Hope and Glory
    Photoshop can only use 3GBs of RAM (it is either that or 4GBs not sure which). Anything more than 5GBs will just be a waste unless you are planning on doing major multitasking.
  4. macrumors 65816


    Feb 15, 2007
    New Orleans
    As Cromulent said, 3gb is currently the maximum RAM that Photoshop will support. CS4 is due out soon, however (probably the end of this year or shortly thereafter) and if Adobe rewrites it for 64-bit support, then it should allow a LOT more RAM usage after that.

    What I did was to get 4x2gb sticks from OWC (8gb) plus the 2 that come with the system by default (costs around $400 or so) and that will give you 10 gigs total, just fine for almost anything other than heavy duty video editing.

  5. macrumors 603


    Oct 2, 2006
    The Land of Hope and Glory
    I remember Adobe doing a keynote in which they said they already an internal build of Photoshop which was 64bit and that they felt the advantages were not that great; which I found odd to say the least. Still we might see a 64 bit build of CS4.
  6. thread starter macrumors newbie

    Jan 26, 2008
    Please give me a swift kick in the ass if this is a bad decision. I haven't quite hit "submit order" yet, but I'm getting damn close.

    I plan on: (via student discount of -$200)
    --2.8 mac 8-core from Apple, adding nothing but wireless, don't need anything else, using the stock video card ATI Radeion 2600 256 mb
    total = $2800

    8gb of RAM for $430
    total = $430....Do I keep the stock 2gb memory or trade-in via OWC policy?

    Western Dig 3200 AAKS 320 gb for OS/Apps
    Western Dig 1500 ADFD 150 gb 10,000 RPM for scratch disk
    Stock 320 gb drive for Data/Photos (I'll back up to external USB hard drives I already own)
    total = $240

    This is a result of 1 mo research, and I'm tired. Just ready to buy so I can get back to photography.

    Thanks, please advise if sounds good.
  7. macrumors 68000

    Sep 22, 2006
    Its not a 64bit app, its impossible for it to use more than 3gbs. Whats the point of 8gbs?
  8. macrumors member

    Jan 12, 2008
    I have read that while the 3GB is the max ram directly addressed (actually just under 4GB including the program overhead itself), CS3 will utilize much more for scratch before using the designated scratch drive - I believe it can read up to 8GB on a Mac w/OS 10.5.

    So....more is better - especially if you want to use other programs concurrently. I've also heard that above 10-12GB is prob. overkill for those running CS3 and other apps.
  9. thread starter macrumors newbie

    Jan 26, 2008
    from barefeats memory test:

    We ran the Retouch Artists benchmark action file using 300MB file in Adobe Photoshop CS3. We observed how much memory was gobbled up during the run. It was the only app running, yet, though we specified only 3GB of memory cache, Activity Monitor reported 13+GB in use! What's happening is that Mac OS X Leopard has the ability to hand over unused memory to apps for caching when they use up their 3.5GB allocation limit. (Ditto for Tiger.)

    When we render the TotalBenchmark with After Effects CS3 with Multiprocessing enabled, it spawns 8 sub processes on our 8-core system which together grab 13+ GB out of our total of 16GB.

    So how much memory should you buy for your Mac Pro? As much as you can afford. I recommend 8GB for most Mac Pro users (8 x 1GB or 4 x 2GB). We have both of our 8-core Mac Pros configured with 16 GB (8 x 2GB). If we could afford it, we'd run 32GB in both.
  10. macrumors member

    Jan 10, 2008
    Absolutely not true.

    The main app can only use 3.5gb ram - however plugins can use more and photoshop will use any additional RAM it can grab as internal scratch before resorting to physical disk for scratch storage.

    If you are working with large images there can definitely be advantages to more than 5GB ram. :)
  11. kem
    macrumors newbie


    Jan 25, 2008
    San Francisco
    I wish people would stop posting uninformed posts about photoshops ram limits. If you work on large photoshop files the more ram you have will definitely help..

    While the app can access 3.5gb directly, however once over that limit it sends to scratch... now CS3 has VM Buffering, so if you have over 4gb of ram photoshop sends what would normally be sent to scratch to the system which stores it into memory. Using that data in memory will give you a noticable speed improvement.

    I think if you do some research, everything you read will tell you if you work on large images get the most ram you can afford.
  12. macrumors regular

    Oct 24, 2007
    Helena, AL
    Always keep the original memory on a machine that is still under warranty. That way if the machine has to go back to Apple or whoever you can return it to it's factory config.
  13. macrumors 68040


    Mar 13, 2007
    PS can use more than 3GB of RAM. Here's the Adobe technote on it:

    From the technote:
    My opinion.....get as much memory as you can afford. OS X loves it.

  14. macrumors regular

    Jan 11, 2008
    Fort Worth, TX
    Paul, all looks good but the ram. We had a discussion a few weeks ago where it was decided to always hold on to the stock apple ram. If anything happens to your MP and you need to take it to an apple store or ship it out for service, you're going to need to take out the 3rd party ram and send it with the stock ram.

    I did the same thing u did ramwise. 4x2GB owc. Until my MP finally arrives, I won't know if I'll run the 8GB or add the 2x1 apple ram for a total of 10GB. Going to need to see how it plays first. If I don't use it, I'm hanging on to it for an apple emergency..
  15. macrumors 68000

    Nov 4, 2003
    yes, we did have this discussion a few weeks ago, and a couple weeks ago, and last week...and after all of the FUD, it was decided that Apple doesn't have any problems with 3rd party RAM as long as it is up to spec, and Apple's "spec" is fairly low. You can send your Mac back to Apple under Apple Care with 3rd party RAM and hard drives in it, and they will not tell you that the problem is your 3rd party hardware unless it actually IS your third party hardware. Quit spreading this myth. There was one guy in singapore or somewhere who said that the local "apple-approved" dealer wouldn't fix his mac because he'd put in 3rd party RAM, but that was singapore, and one guy.

    I've personally sent in 2 macs with 3rd party RAM, and one of those was a mini that i'd accidentally scraped the case of trying to get my putty knife in to pry it open. They replaced the failed (apple-supplied) hard drive and sent it back with no comments on the non-apple RAM upgrade I'd done.

    Sell your Apple-installed RAM on ebay to some dummy who thinks it is "better" and will pay more for it than it is worth. Please.
  16. macrumors regular

    May 6, 2006
    Madrid, Spain
    I have posted here the perf article quoted above several times.
    Get the more ram, you won't regret it.

    Here is how to do the math, 3GB for CS3, 1GB for your Plugins if you use any, then (M) for you max file size you will have open (Tiff 2GB limit) and the 2 GB ram OS X needs to browse the web ans such. :)

    This is what I do all day! and I run lot's of scripts on my images so I need up-to 4 files opened at the same time and some scale out to 500MBs each. :eek:

    Trust me, you will not regret the extra ram! Also if you do any video editing, you will see how this will get used up... if you apply any filters on video, you will need lot's of ram plus RAID!

    Hope it helps.
  17. macrumors 68020

    Mike Teezie

    Nov 20, 2002
    If you can't do both, I'd get the 8 gigs of ram now, and the scratch drive.

    Then, I would add more ram as I could afford it.

    It should be noted that Photoshop users' needs vary wildly from one person to the next. I run Bridge in conjunction with Photoshop, and it seems to eat ram up horribly. I would run 32 gigs of ram in a heartbeat if I could afford it.

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