Radeon Pro 570 and eGPU or Pro 580?

Discussion in 'iMac' started by scotttnz, Sep 21, 2017.

  1. scotttnz macrumors 6502a

    Joined:
    Dec 16, 2012
    Location:
    Auckland, New Zealand
    #1
    So I'm intending to buy a 27" iMac soon, and homing in on the configuration to purchase. I thought I had settled on an i5 3.8GHz with the Radeon Pro 580, but I have started to wonder if a lower spec machine with an eGPU might be the way to go. Any thoughts and opinions from the community would be appreciated.
    • Usage with be Lightroom, Photoshop, Web browsing, office apps, and some gaming. I also run a Parallels Windows VM for some work apps, but I am using it less and less. I will probably install Windows 10 in bootcamp to play Age of Empires 4 when it is released.
    • I love, and intend to keep my Philips 40" 4K monitor connected to the new iMac. This requires a display port 1.2 connection to run at 60Hz. A big part of my thinking with going with the 580 originally was that I might need the extra power to comfortably drive the extra 4K display. Would using an eGPU give me more flexibility and performance?
    • I will be getting a BTO with 512GB SSD and adding 16GB of 3rd party RAM with either option.
    • I'm not currently CPU constrained on my Mac Pro with single 6 core X5650, any of the new CPU options will give me double the single core performance, and higher multi core, so I'm not too concerned about the CPU.
    • Cool and quiet is a bigger concern for me than maximum performance.
     
  2. Samuelsan2001 macrumors 604

    Joined:
    Oct 24, 2013
    #2
    Just about any SSD equipped iMac will do that use case without breaking sweat I seriously doubt an egpu will ever be needed by you and even the 580 is probably overkill. Hell the 12 inch MacBook could probably do your workload without skipping a beat.

    The only thing you will feel the benefit of better graphics for will be your occasional gaming and that seems low on your priority list.

    I would go with the 580 myself it will easily run an extra 4K screen or even an extra 5k one and modern games at a decent frame rate. If in a few years you need an egpu to upgrade it then fair enough but that seems unlikely to be soon with what you want it for.
     
  3. scotttnz thread starter macrumors 6502a

    Joined:
    Dec 16, 2012
    Location:
    Auckland, New Zealand
    #3
    Thanks for your response.

    In some ways I agree that my usage is not heavy, but on the other hand I am often using around 20Gb or more of RAM, which is what has led me to the 27” iMac. With most other Macs more than 16GB is either impossible (MacBook and MacBook Pro) or not user upgradable (21” iMac) and Apple charge ridiculous amounts of money for BTO memory upgrades.
    I don’t game a lot, but when I do, I want a good experience.
    I think you are right though, the 580 would be more future proof, with the faster processor etc, and I’d still have the option of adding an egpu in the future.
     
  4. Samuelsan2001 macrumors 604

    Joined:
    Oct 24, 2013
    #4
    Ram in OS X is a weird thing, it actively uses as much RAM as is available, on the eminently reasonable grounds that unused RAM is wasted. That means much of what is loaded into your RAM is “just in case” it will speed things up when needed, this cache is however available for use by any process needing RAM when it’s needed so you may be using 20gb RAM, but a great deal of that may be still available for critical processes and the same workload on 8gb of RAM will work just as well with no slowdowns.

    Now I know you do photo editing and that can use large amounts of RAM with huge picture libraries, I have yet to see need for more than 16gb of RAM for any photo editing though to be honest, of course you may need lots of ram I just can’t tell from what you have written here, however writing that your system currently uses 20gb is no indication of what you need.
     
  5. theluggage macrumors 68040

    Joined:
    Jul 29, 2011
    #5
    As @Samuelsan2001 said - Mac OS uses "spare" RAM to cache frequently used files - if you want to know if you're "really" running out of memory then look at "Memory pressure" and "Swap used" (swap should preferably be zero). Having more memory for cache does speed things up but for most users with non-specialist needs, going above 16GB will bring rapidly diminishing returns, esp. if your files are on superfast SSD to start with.

    "Photoshop" is a piece of string: some people out there are compositing layer upon layer of high-resolution images and need all the RAM they can eat, others are just cropping and retouching individual photos. Pro audio with lots of samples is another RAM-guzzler. I think the only thing you're doing that is potentially RAM-heavy is Parallels, but I've been using that for the occasional windows application on an 8GB machine for years...

    However, with the iMac 27", 24GB is the sweet spot, but only because you can get the 8GB version and then add 16GB of third-party RAM for less than Apple wants for an upgrade to 16GB. Then if you do need more you can upgrade to 32, 48 or 64GB at your leisure.
     
  6. scotttnz thread starter macrumors 6502a

    Joined:
    Dec 16, 2012
    Location:
    Auckland, New Zealand
    #6
    Thanks for this.

    As an experiment, today I removed one of the 8GB modules from my Mac Pro, reducing it to 16GB RAM. I’ve thrown everything I normally do and more at it and memory pressure has stayed green. Now I’m seriously considering a MacBook Pro again to reduce my desk footprint and give me the option of portability.
     
  7. jeyf macrumors 65816

    Joined:
    Jan 20, 2009
    #7
    For a 2015 iMac with osx10.11.5 and 16G ram, running 4 or 5 VMware virtual machines
    using the Apple Server 5.1.5 STATS I have not noticed it even coming close to using 8G ram much less the full 16G. Looking over the last 7 days it runs close to 5G RAM

    dont know if this helps
     
  8. scotttnz thread starter macrumors 6502a

    Joined:
    Dec 16, 2012
    Location:
    Auckland, New Zealand
    #8
    Thanks to all for the input. I now feel reassured that 16GB will be enough for me for the foreseeable future, so I decided to go with a MacBook Pro. Picked up the top spec, stock 15” today, with the 2.9GHz quad core i7, 16GB, and 512GB SSD. Now to sell the old Mac Pro....
     
  9. kyledkearney macrumors newbie

    Joined:
    Feb 13, 2018
    #9
    I actually do your entire workload off of a 12” MacBook, plus editing 4K video in Final Cut Pro. it does it with out skipping a beat. It’s the base 2015 model, the only real reason you would ever need the 580 is because of your workload ramping up in the next 5 years, to pro videographer levels.
     

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8 September 21, 2017