iMac 27 or 21?

Discussion in 'iMac' started by and 4096 others like this, Jun 7, 2018.

  1. and 4096 others like this macrumors member

    and 4096 others like this

    Jan 26, 2018

    I want to buy my first iMac and I don't know which one should I choose...

    Obviously, 27 have bigger screen, but in term of performance which one will be better?:

    21,5" 4K, i5 3,4 GHz, 8 GB ram, 1TB Fusion Drive, Radeon 560


    27" 5K, i5 3,4 GHz, 8 GB ram, 1 TB Fusion Drive, Radeon 570

    Specification is very similar, but 21,5 have lower resolution, so maybe it's faster? Sometimes I play Starcraft 2, will 21,5" iMac handle with this game in medium/high settings?
    There was a time, when 27" iMac had a problem with dust inside its screen. Is this still and issue?

    Is it worth to buy bigger iMac just for better GPU?
  2. casperes1996 macrumors 68040


    Jan 26, 2014
    Horsens, Denmark
    Neither of those will play very many games at native resolution, so you'll set the game to run at a lower resolution. The 27" iMac is a lot nicer in my opinion, and you can upgrade the RAM later on if need be. - Furthermore, I really recommend getting a 2TB Fusion Drive instead. The 1TB version only comes with 24GB of SSD space, so 90% of what you do will run at HDD speeds. The 2 and 3TB Fusion Drives come with 128GB of SSD space, which is enough that it can cache most everything intelligently.

    If you have the budget, 27" with bigger Fusion or full SSD.
    If you need something cheaper, 21" with bigger Fusion or SSD.

    The Fusion/SSD upgrade is the biggest one.

    Both should handle StarCraft just fine at high settings, as long as you don't expect to play at 5k.

    I've heard no reports of dust issues.
  3. colodane macrumors 6502a


    Nov 11, 2012
    The performance of these two machines will be essentially identical.

    More importantly, I would not recommend either one. Please avoid the 1 TB fusion drive. The SSD partition is very small. See several threads in this forum for more detail.

    If possible, purchase one with a SSD.

    The other major difference is that the RAM in the 21.5 inch is not user upgradeable. So if you purchase it, make sure you specify all the RAM you might possibly need during the initial purchase.
  4. and 4096 others like this thread starter macrumors member

    and 4096 others like this

    Jan 26, 2018
    Thank you for your advices! Unfortunately, my budget is not as high to get 2TB FD. At first I thought about getting some Windows AIO, but I want to try iMac (which price is much higher compared to DELL etc). Starcraft is one and only game I play, so no need to think about other, more demand games.

    I know about 1TB with smaller SSD, but if I wan't to configure it, I need to do this at Apple Online Store or one of Premium Resellers. Problem is, that in my country price is like $300 higher than in regular shop, where I can't configure it...

    For example 21,5" 4K, i5 3,4 GHz, 8 GB ram, 1TB Fusion Drive, Radeon 560 cost $2050, but same iMac at regular shop goes for $1750, If I go for 256 GB SSD, it cost another $130...

    So long story short, this iMac with 256 GB SSD would cost me almost $2200. So upgrade from 1TB Fusion Drive to 256 SSD would cost me $450 total...

    Same thing goes for 27" iMac which cost almost $2450 at AOS, but $2100 at regular shop. Upgrade from 1TB Fusion Drive to 256 SSD cost again $130...

    As you can see the only option is 1TB Fusion Drive, because regular shops have only stock configurations, no upgrade option.

    Or maybe I should wait for another iteration of iMac and Apple finally will drop prices or make 1TB Fusion drive standard (instead of 5400 rpm drive) and 256 SSD standard for higher configuration :(
  5. jksu macrumors regular

    Nov 26, 2009
    get the 27”. the screen is gorgeous. you’ll regret getting the 21”.

    if storage space or speed becomes an issue you can pick up a 250gb external usb-c SSD for $150

    and yes upgrading ram is doable and easy on the 27”
  6. tubeexperience macrumors 68040

    Feb 17, 2016
    Get the cheapest storage and memory configuration.

    Afterwards, you can then upgrade the storage and memory yourself for cheaper.
  7. casperes1996 macrumors 68040


    Jan 26, 2014
    Horsens, Denmark

    All this considered; Get the 5K as you described and get an external SSD when your budget allows for it. Fact is that it's actually going to be a relatively bad experience running macOS off a spinning HDD at this point, and the 24GB size of the SSD in the 1TB Fusion, means that's what you'll be doing most of the time. After you open apps and files, it'll be a fast computer, but initial opening will be relatively slow. External SSDs with USB or Thunderbolt can be really fast and give a good enough experience though, and you can get some sleek and tiny ones that you don't even notice.
  8. Jerion, Jun 7, 2018
    Last edited: Jun 7, 2018

    Jerion macrumors member

    Mar 31, 2016
    Unless your budget precludes it, start at the 27" and don't look back. The screen quality and real estate is incredible. The Fusion Drive/SSD thing is important to consider, but that can be worked around down the road if you don't have the funds to address it up front.

    Within the 'stock' 27" lineup, the big differentiators are:

    i5 vs i7


    Radeon Pro 570/575/580

    The i5 vs i7 differences will be meaningless for most people. The i7 is beneficial to apps that need heavy lifting, but the i5 options won't exactly be a slouch either. You probably won't have to care about the CPU, really. They're all More Than Good Enough™ and will continue to be More Than Good Enough™ for years to come.

    The GPU is going to be your first "choke point" as the machine ages- it will be left behind by AAA gaming in a few years. StarCraft 2 isn't a hugely demanding game these days, so even the 570 should be able to handle it and not really work too hard. However, you might move to play something else in the future, so with that in mind...

    GPUs are most easily compared by their teraflop (TFLOP) numbers (this doesn't represent everything a GPU can do, but it's an easy metric for overall ability). If my source is right, the Radeon Pro 570 will give you around 3.5 TFLOPS, the 575 around 4.5, and the 580 around 6 (roughly equivalent to an Xbox One X, and closing in on a GeForce GTX 1070 in PC land). You will not be able to play the newest games (or even new-ish games) at 5K resolution. It's just not going to happen. Fortunately, 2560x1440 -- exactly half of the native 5K resolution -- still looks fabulous on a 27" screen. And these GPUs can handle gaming at that res, with steadily increasing degrees of comfort and performance as you go up the price ladder.

    Hope the above helps you make a decision. Enjoy the machine! :)
  9. and 4096 others like this thread starter macrumors member

    and 4096 others like this

    Jan 26, 2018

    thank you once again for helping me to pick right device. Appreciate this :)

    The thing is, I think I will go for option "C" - 1TB Fusion Drive + external SSD (USB-C). This would be best solution in my case... But I still don't know should I spend more money for 27". It looks cool (right now, I am using 27" monitor, so I like a lot of space) but I read about dust problem in 27" (never about 21"). Here are some samples:

    And to be honest, I found a lot of posts like this... I don't wan't to spend a lot of money for device, that will look like that after only 2 years ;/ How is this possible, that post like this shows up since 2013 or 2014, and here we are 4-5 year later they are still accurate ;(
  10. casperes1996 macrumors 68040


    Jan 26, 2014
    Horsens, Denmark

    Well, I've had my 27" 5K iMac for 3.5 years now and it certainly has no such issues. It would annoy the pants off me if it did, but I can say that it's at least not a universal issue. My 5K 1st gen is perfect as far as the screen is concerned.

    Benefits of the 27" are:
    Better GPU (A fair bump in GPU performance)
    Higher resolution screen
    Better cooling to ensure that your CPU gets to run at turbo more frequently (Though the GPU is also a higher TDP variant so it'll get hotter; Thus the better cooling is needed in the first place - but it's a cooling system that can handle much higher configurations)
    User upgradable RAM if you need more a few years from now.
  11. and 4096 others like this thread starter macrumors member

    and 4096 others like this

    Jan 26, 2018
    Well I have one more question...

    I checked a lot of older post here and there and found out, that Fusion Drive (1TB) used to be 128 GB SSD, next 24 GB SSD (I think it was in 2015 model?) and now (in my country) Apple website shows 32 GB SSD. So they did a little upgrade of downgraded 1 TB Fusion Drive? Also - are we talking about 5400 rpm hdd or 7200 hdd in 1 TB Fusion Drive for 21 and 27 iMac?

    How much of storage take macOS alone or with stock apps? I will install only Starcraft 1, Starcraft 2, VLC and that's all... What I am thinking of is - if they put 32 GB of SSD and 7200 rpm drive, then for my needs this will be ok... Although on Windows Starcraft 2 took 14 GB storage, and right now I have Samsung evo 830 or 850
  12. casperes1996 macrumors 68040


    Jan 26, 2014
    Horsens, Denmark

    You're right the Fusion Drive has changed over time. In my 2014 iMac, the 1TB I have is a 128GB SSD with a 1TB HDD. I hadn't heard of the jump back up to 32GB, but I still don't think it's enough. 64 and we may be talking, but honestly I don't think any less than 128 is OK if I'm honest.

    Regarding the size of macOS, I'm going to give you a very inaccurate answer. - I think it's around 16GB. In Storage Management it does say a size next to "System" but this is affected by a lot of things, like number of extensions installed. I'm guessing around 16GB though. I'm sure a more accurate estimate can be found elsewhere though.

    The spinning disks in the 21.5" iMac are 5400RPM. In the 27" iMac they are 7200RPM.
    --- Post Merged, Jun 8, 2018 ---

    If you already have these drives, you can just buy a good USB-C drive caddy that supports UASP and fast file transfers, and plug in your existing SSD
  13. Fishrrman macrumors P6


    Feb 20, 2009
    Get the 27".
    Don't get a 1tb fusion drive. Get the 2tb version instead (for the 128gb SSD portion).

    Actually, you might be able to get the 256gb internal SSD version for LESS than the 2tb fusion.
    It runs fast and will keep running fast over the life of the computer.
    Add more storage when you need it via USB3.
  14. kschendel macrumors 65816

    Dec 9, 2014
    I'm no fan of the 1Tb Fusion, but for "general" use (office stuff, web, email, maybe some gaming) I don't think it's necessarily a deal breaker. I'd advise going to straight SSD, or one of the larger Fusion setups if you really need the storage space. But, if you simply can't afford it, or must have the 1 Tb storage space, I think the 1 Tb Fusion is survivable long enough that you can save up for an outboard SSD. If you already have one, so much the better.

    The 1 Tb 5400 spinner (non-Fusion) on the base 21.5" is another story. I don't advise buying that one at all, unless you are seriously hard-limited on cash flow.
  15. pier macrumors 6502a


    Feb 7, 2009
    Whatever you do get an SSD.

    You can buy a SATA SSD and connect it via USB3 if you need more storage later.
  16. tubeexperience macrumors 68040

    Feb 17, 2016
  17. nambuccaheadsau macrumors 68000


    Oct 19, 2007
    Nambucca Heads Australia
  18. wardie macrumors regular

    Aug 18, 2008
    If on an old computer for sure. But a new buy - surely not, versus order with SSD inside? If you order a mac with HDD it will have a drive with a SATA interface, then you end up swapping it out for a SATA-III interface SSD drive not a PCIe drive, limiting its max bandwidth a lot. Sure you will maybe save a few $ but you’ll have to open up your mac to replace the drive (warranty etc plus professional cost unless you are hardcore DIY) and also won’t exploit PCIe speeds of solid state once done.
  19. tubeexperience, Jun 8, 2018
    Last edited: Jun 8, 2018

    tubeexperience macrumors 68040

    Feb 17, 2016

    (roommate in the background)

    ...still waiting for the SSD to arrive.


    You can get a 1TB SSD for ~$200.

    Apple charges $700.

    Sure, it's not PCIe, but I am sure many people would rather save the money.
  20. and 4096 others like this thread starter macrumors member

    and 4096 others like this

    Jan 26, 2018
    Thank you for all advices and answers.

    I have to point once again, that in my country in regular shop where prices are more affordable, there is no personal configuration option, only stock iMac (3x 21,5" and 3x 27"). If someone want to configure iMac, have to pick either AOS or Premium Reseller. So If I go for upgrade from 1 TB FD to 256 GB SSD or 2 TB FD, I have to pay like $450-500 (difference between AOS price and regular shop ~$300-350 + cost of configuration cheapest SSD option at AOS ~$130) - it's not worth it...

    Upgrade right now is not an option. I don't want to destroy something, even if it's easy. I will wait till warranty expire.
  21. tubeexperience macrumors 68040

    Feb 17, 2016
    The timing doesn't really matter because, if you destroy it, the warranty is over anyway.

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