iMac 5k - 8/16 Gb and 290X/295X?

Discussion in 'iMac' started by blufrog, Mar 7, 2015.

  1. blufrog, Mar 7, 2015
    Last edited: Mar 7, 2015

    blufrog macrumors member

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    Dec 19, 2014
    #1
    Having purchased an rMBP 13" (8/256) a couple of months ago and loving it ever since, I'm seriously looking at the 5k iMac.

    The CPU is a no-brainer - quad core i7.

    What I can't decide upon is whether it is worth getting more than 8 Gb RAM, and upgrade the 290X to the 295X.

    First, the memory. On my rMBP it does use the swap file (most I've seen is 400 Mb), but because it is SSD backed, the performance hit (if there is any!) is unnoticeable. Is it worth upgrading from 8 Gb to 16 Gb? The "memory pressure" graph is usually less than half at any time. I have a graphics-intensive Java application that pushes this to maybe 2/3 the way, but this was when I was testing it and opened everything I could. Performance seemed excellent even when I tried to kill it.

    Second, the GPU. Yes, I will want to do gaming on the iMac. That said, my current PC has 2 Gb graphics card (2 Gb AMD R290) which I understand is very close to the M290X found in the iMac. I'm very happy with this card in my PC.

    Looking at raw tech specs, the M290X posts higher fill rate than the M295X, so it seems the only real difference is the video memory.

    Allowing for the fact the iMac is pushing 5k, is there really any difference between the two cards? In other words... is the 295X worth the extra $300? It would seem not.

    Regarding the storage, apparently if you go SSD it is soldered to the board, but if you go Fusion drive you can replace it with OTS SSD? Is this correct? If so, is it worth doing?

    Any suggestions for running external storage via Thunderbolt? At the moment I use a network share for most stuff, and a USB drive for TM backups.
     
  2. redheeler macrumors 603

    redheeler

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    Oct 17, 2014
    #2
    I would recommend you go with the M295X as the high-res screen does put some extra stress on the GPU and the M295X is known to reduce lag. As for the RAM, go with 8 GB for now. You can always upgrade if you need to in the future.

    PCIe SSDs are not soldered to the board, they are replaceable. However, you do need to unglue and re-glue the display to get to it and that's not an easy job.
     
  3. blufrog thread starter macrumors member

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    #3
    Good to know regarding the SSD!

    Just doing a bit more research on the 295X - there are more than a few reports of it overheating and suffering thermal throttling. Is this as widespread as it seems or a case of 1 bad report having the weight of 1000?
     
  4. yjchua95 macrumors 604

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    #4
    It's not as widespread as what people say.

    I've a 5K iMac (i7/32 - DIY upgraded from 16/512GB SSD/M295X), and it only heats up when doing 4K cinematography and gaming. But the fans are almost inaudible most of the time compared to working about the same stuff on my 15" rMBP.
     
  5. Meister Suspended

    Meister

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    Oct 10, 2013
    #5
    Yosemite and Mavericks always swap. There is no reason to upgrade memory when buying an iMac.

    ----------

    The ssd is theoratically replaceable, but the connectors necessary are not available yet. Also replacing the ssd in the iMac 5k is extremely difficult (even for experienced nerds) and a lot can go wrong. Configure the ssd size you need at purchase. Do not count on the replaceability of the ssd!

    ----------

    It does perform thermal throteling. That is not a myth but a fact. An iMac 5k will not reach the same performance as a regular PC with the same specs.
     
  6. blufrog thread starter macrumors member

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    Dec 19, 2014
    #6
    Thanks for the replies! Interesting regarding the swapping.

    If the 295X is certain to throttle due to thermal limits, is there much point paying the extra for it?

    I appreciate the iMac won't out-perform a gaming PC as it uses mobile components for a start (they are always lower performance regardless of anything else) but if I can get "reasonable" performance from 3D applications then that is what I'm looking for.

    What I'm most interested in is reliability. If the 295X runs hotter and has to throttle due to heat, then it will obviously fail sooner than a card that never gets hot enough to throttle in the first place. Also, thermal throttling can be aggressive, so during throttling performance can be dire compared to a lower end card that doesn't throttle in use.

    How does the 290X compare in this regard?
     
  7. blufrog thread starter macrumors member

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    Dec 19, 2014
    #7
    I have been carefully examining the 5k iMac the last week or so, and from the benchmarks run on the iMac vs. same or similar benchmarks run on my current desktop computer, I've concluded:

    * Intel i7 4.0 GHz has similar perf to AMD 8350 4.0 GHz
    * M295X is more powerful than R9 270 desktop card given it is pushing 14M pixels vs. 2M on my desktop
    * By the time I've upgraded to nVidia 980 and a 4k display, I'm not far off the price of an iMac with 5k display
    * The iMac has superior display tech vs. every 4k display in existence (seems they all employ dual panel)
    * To build equivalent Intel based system to iMac spec is the same price, or significantly higher if a Dell 5k display is pursued.

    Given the revelation also about the thermal paste in the 5k iMac, it would seem the thermal issue could be resolved.

    I think overall, the iMac 5k represents great value, so one will be placed on order! :cool:
     
  8. roadkill401 macrumors 6502

    roadkill401

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    #8
    I would say that the 'hype' about the 290x not working fast enough to power the 5k screen without lag is also well overstated. I have yet to ever see any of these 'common' problems that like to get thrown around here like they are fact.

    I would hazard to guess that many of the people here that are quoting problems with this 290x graphics card have

    1. never even owned the unit
    2. never bothered to do any diagnostics if an issue occured to see what the cause was. (was it hardware, software or a Stupid User issue)
    3. like to feel part of the crowd by simply repeating what they heard because if it was posted on a thread it must be true.

    I have ordered and worked with an 8gb riMac, and can say from first hand experience that it does work quite well most of the time, but if you are running multiple VM's, you need 16. If you have Photoshop, Illustrator and DreamWeaver open at the same time and using it to develop a website, you need 16. If you are trying to use Lightroom and browse though a large collection, then you will benefit from 16.
     
  9. fathergll macrumors 6502a

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    Sep 3, 2014
    #9
    I've owned a 290x with 24 GB of ram since November. Factory OS, no migration assistant or anything and there is lag at times. Seems more of a Yosemite issue than anything.
     
  10. blufrog thread starter macrumors member

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    Dec 19, 2014
    #10
    Couple of questions:

    * What kind of storage do you have (SSD or Fusion)
    * When do you see lag?

    My rMBP will beach ball occassionally for no apparent reason (8 Gb RAM, SSD), but is smooth the rest of the time (sure, things like swapping desktops is not perfectly smooth animation, but TBH I don't expect it to be). Calling up Launcher is smooth 99% of the time, but I'm sure if I do it often enough even that will glitch.

    The reason I ask about the storage is because if the HD is asleep, it will spin down, and due to the hardware architecture the sytem can freeze for a moment whilst it waits for it to spin up and reach ready state again (even SSD will do this, but not as noticable as it will wake extremely quickly).

    I plan to get the 8 Gb model, and upgrade it to 24 Gb, because I will want to run a VM and run some programs with large memory requirements.
     
  11. fathergll macrumors 6502a

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    Sep 3, 2014
    #11

    * What kind of storage do you have (SSD or Fusion)

    • 1 TB Fusion. I have the base model.

    * When do you see lag?


    • Sometimes in finder there is obvious UI lag when browsing folders.
    • Preview many times there is lag opening pictures
    • When logged into my admin account I get a beachball everytime when I click on system preferences to the display area setting. It's not just the changing of the resolution but just getting into the actual screen it hangs and does a beachball. This does not occur on my second account.



    Yes I think I know what you are talking about. I've seen this on my 2012 Macbook Air(256 ssd) when waking the system up but my Air never has lag once the system is awake for 10 secs. Unless the HD portion of fusion keeps going to sleep im not sure why it would do that.

    Keep in mind there are many times when my base iMac is lighting quick as well browsing folder...etc. I honestly don't think i've noticed the fan even go on since i've had the computer. It stays very cool(well for something thats pushing a 5k display in an enclosed unit.)
     
  12. fathergll macrumors 6502a

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    Sep 3, 2014
    #12
    Im running a Windows 7 VM on it. Works pretty well. Windows doesn't scale as well as Yosemite(not a surprise). Windows 10 VM has been a hit and miss. One time it render my entire screen black and I couldn't get out of it for a while.

    If I had a all SSD I might considering running Windows 7 in bootcamp.
     
  13. blufrog thread starter macrumors member

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    Dec 19, 2014
    #13
    Regarding the max settable display resolution in OSX, does it do the scaling thing like the rMBP does (where the highest desktop res is still less than native) or can you actually set native resolution? How does this work?
     
  14. yjchua95 macrumors 604

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    #14
    It's like the rMBP.
     
  15. blufrog thread starter macrumors member

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    Dec 19, 2014
    #15
    I ordered an iMac 5k:

    * i7 4.0 GHz
    * 8 Gb RAM (will upgrade it to 24 Gb)
    * 256 Gb SSD
    * M295X

    :cool:
     
  16. HelixFramer macrumors newbie

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    Aug 8, 2015
    #16
    I'm very interested, how has it worked out for you? I'm in a similar position right now in terms of deciding on which graphics processor to get in conjunction with the i7 4.0 GHz, 8 Gb RAM (but then upgraded to 24 or 32) and 3tb fusion drive (for large internal audio storage). I'm planning to run graphics intensive image, video, and sound programs as well as games.
     
  17. jerwin macrumors 65816

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    Jun 13, 2015
    #17
    Hold the option key down while selecting the "scaled" radio button. Apparently this is quite useful when trying to force certain games into 5k mode. Otherwise, it's too small for comfort.

    Screen Shot 1.png Screen Shot.png
     
  18. aliensporebomb macrumors 68000

    aliensporebomb

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    #18
    Thoughts: running the i7 4.0 ghz machine with 24 gigabytes of ram. CPU has been up almost 15 days now and am running 24 gigabytes of ram on this unit, my memory pressure is 11%.

    I'm running the 290x (I wanted the 295 but I could either have the i5 and the 295 or the i7 and the 290x and I NEED the i7 for some of the critical apps I use). Gaming wise I am able to run X-Plane 10 at 5k and run Elite Dangerous smoothly at 4k (I've run it at 5k and it still plays fine just not quite as smoothly). This is under Mac OS X.

    Any other questions? It geekbenches well over 15,000 if those numbers mean anything - close to 16,000 actually (I'm just running the 32-bit version so it likely benches over 16k in the 64-bit edition).
     
  19. jerwin macrumors 65816

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    #19
    My swap is 0 bytes, but I tend to turn off my computer at night. What's your swap used, aliensporebomb? OSX tends to compress memory before swapping.
     
  20. Glockworkorange macrumors regular

    Glockworkorange

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    #20
    El Capitan fixes the 290x lag. This from a user with a 290X 1TB fusion running the latest El Cap beta. It seems lag isn't really an issue with the new OS. Might be the move to Metal.
     
  21. aevan, Aug 9, 2015
    Last edited: Aug 9, 2015

    aevan macrumors 68000

    aevan

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    #21
    Note: I just realised this was posted months ago and that the OP has already made his purchase. However I will keep my post as it may benefit someone.


    While there are situations where this is true, might I ask how is an i7 an "no brainer"? You do know that it depends on what apps are you using? For example, in games (since you mention you want to do gaming) - you won't see the difference. In a lot of apps - also. In video rendering apps, on the other hand, you'll see a big difference. I'm in no way saying the i7 is not a great choice, but for someone who is not sure if he needs more than 8Gb of RAM, are you sure you know what the difference between an i5 and an i7 is and where that difference is noticeable? The only reason I'm asking is that I know a lot of people who automatically think the CPU upgrade is the most important one, while for most apps the difference is negligible. Then again, if you render 3D or video, or do sound processing, the i7 will be quite a bit faster thanks to Hyper-Threading.


    RAM can easily be upgraded later (and at cheaper prices than getting it from Apple) so start with 8 and see if you need more later. It's easy - if you don't KNOW you need more, you probably don't. 8 is enough for most things.

    Even with 32Gb, the OS will sometimes use the swap file. Don't worry about it. The only thing you should monitor to see if you need more is Memory Pressure in the Activity Monitor. As long as it's green - you're good.

    The R9 290 in your PC is not the same as the R9 M290X in the iMac. Notice the "M"? It stands for Mobile, and that means lower performance. The desktop R9 290 is a LOT faster than both the M290X and M295X. That doesn't mean you can't game on M290X and M295X because you can. The M290X performance in the iMac is very close to HD 7870 desktop Radeon.

    Depending on what you do. You're not going to game in 5K on either of these cards, but at 1080p and 1440p instead. The M290X can handle modern games, the M295X can handle them at a higher resolution, but neither can come close to 5K. As for non gaming - both handle 5K fine and there isn't much difference. GPU-dependent apps can benefit from a faster GPU but how much, hard to say. Again - depends on the app.

    You can't replace anything other than RAM without voiding the warranty. And even if you don't care about warranty, the process of replacing the drive is not easy and a lot of things can go wrong. I suggest you get the drive you want from Apple and stick with it.

    Thunderbolt SSDs, while a bit slower than internal SSDs are great and fast (and expensive). But if you can afford them, you won't see any practical difference compared to an internal SSD.
     
  22. aliensporebomb macrumors 68000

    aliensporebomb

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    #22
    9.33 gigs last I checked a few minutes ago.
     
  23. aliensporebomb macrumors 68000

    aliensporebomb

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    #23
    Update: can those who had "lag" in the 290x describe a situation where I could easily duplicate this condition? I've yet to see any lag as described.
     
  24. jerwin macrumors 65816

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    #24
    I believe it consists of making sure all the transparency effects are turned on, and pressing the expose button (f3) repeatedly.
     
  25. Meister Suspended

    Meister

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    #25
    Turning off at night might be the reason.
     

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