iMac 27" late 15 / 2TB Fusion -> SSD?

Discussion in 'iMac' started by zerozoneice, Jan 5, 2016.

  1. zerozoneice macrumors regular

    Joined:
    Jun 26, 2013
    #1
    So, is there a way, official or not to swap the 2TB fusion setup of a late '15 Skylake 5K 27" with a single SSD?
    Don't care about migrating data or anything, i backup to external anyway. Just remove the hardware (128 SSD + 2TB HDD) and replace it with a, say 2TB EVO SSD?

    Does that thermal connector issue still apply? The one that is needed in order to properly control the fan?
    Thanks!
     
  2. MadDane macrumors 6502a

    Joined:
    Apr 5, 2015
    #2
    Do you currently own the machine or are you considering buying one?

    I would advise against taking out the 128GB SSD. I really don't see what you would gain by doing that? It is much faster than even the Samsung SSD. But yes, it is possible. iFixit has a guide how to do it right here: https://www.ifixit.com/Guide/iMac+Intel+27-Inch+Retina+5K+Display+Hard+Drive+Replacement/30522

    This is the late 2014 model. But the steps for the late 2015 will be the same. Then you also need a 2.5" to 3.5" converter. Those can be had for cheap on Amazon or eBay.
     
  3. zerozoneice thread starter macrumors regular

    Joined:
    Jun 26, 2013
    #3
    Yes, i own the machine. Thx for the answer, but:

    - What speeds are to be expected from a 3rd party SSD and why?
    - Can the Apple 128GB SSD remain inside and only the HDD be swapped with a 3rd party SSD?

    I owned a rMBPro late '13 with 512GB SSD before and i was kind of spoiled by its speed, esp. when waking up from sleep, booting or general loading/moving stuff around.

    Thx!
     
  4. Samuelsan2001 macrumors 603

    Joined:
    Oct 24, 2013
    #4
    The Third party SSD will have to connect to the SATA 3 connection (apples PCIe connector is proprietry and so there are no third party drives that connect to it) and so be limited by bandwidth to sequential read/writes of around 550MB/sec.

    Yes you should be able to swap the HDD for an SSD (see link tio iFixit guide posted by MadDane above) and you can even then create your own fusion drive so all your most used stuff would be on the super fast PCIe SSD and the rest would be on the slightly slower SATA 3 you installed allowing the mac to optimise for speed.

    The fusion drive sholud feel just as fast for most usage.
     
  5. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #5
    No official way as its not considered a user replaceable part but you may find a computer repair shop willing to do the work.
     
  6. Sirmausalot macrumors 6502a

    Sirmausalot

    Joined:
    Sep 1, 2007
    #6
    You are much, much better off running a new SSD from USB 3.0 or Thunderbolt. But yes, in theory you could remove the hard disk portion of the internal drive and replace with an SSD. But it is unlikely to be faster than an external solution. You can check out OWC and iFixit for more information on how to do the very, very difficult swap. As for the SSD, you'd need to check the read/write speeds from the manufacturers.

    Again, external is the way to go, even if you use it for a boot drive.

     
  7. zerozoneice thread starter macrumors regular

    Joined:
    Jun 26, 2013
    #7
    thx @ all!
    the store i bought the machine from (and offered the warranty) can do the swap, i have the option to bring my SSD or use theirs (more expensive). They can even do a HDD->SSD swap for a late 2012 21.5", which is painful with its 5400rpm. Oh wait, as painful as the late 2015 4K 21.5" :D
     
  8. maflynn Moderator

    maflynn

    Staff Member

    Joined:
    May 3, 2009
    Location:
    Boston
    #8
    That's cool that the retailer from whom you bought it can upgrade your iMac and provide a warranty on the work. That makes life a lot easier for you
     
  9. zerozoneice thread starter macrumors regular

    Joined:
    Jun 26, 2013
  10. Brian33 macrumors 6502a

    Joined:
    Apr 30, 2008
    Location:
    USA (Virginia)
    #10
    I'm wondering this as well. However, the product you link to is an M.2 NVMe card that uses "four PCIe 3.0 lanes," and I read somewhere (can't recall where) that the iMac uses four PCIe 2.0 lanes. All the M.2 products I found with a quick search seem to use PCIe 3.0.

    I don't know about the differences between PCIe 2.0 and 3.0. Does anyone have an opinion on whether Samsung's NVMe card for PCIe 3.0 would work in Apple's PCIe 2.0 slot? Personally, I doubt it...
     
  11. zerozoneice, Jan 11, 2016
    Last edited: Jan 11, 2016

    zerozoneice thread starter macrumors regular

    Joined:
    Jun 26, 2013
    #11
    indeed, the late '15 skylakes have PCIe 2.0 w/4 lanes, whereas the 3rd party SSDs operate on PCIe 3.0 4x. NVMe being the SSD controller and PCIe x.0 the board interface...
    Aren't they backwards compatible?

    Seems to be 2 questions that need to be answered:
    - does the controller/connectivity of the new NVMe SSDs allow for simple PnP on the iMac board?
    - does the PCIe 2.0 vs 3.0 hinder/limit performance, regardless of available lane count? (both 4x)

    Check this article:
    http://www.overclock.net/t/1489684/ssd-interface-comparison-pci-express-vs-sata

    [​IMG]

    iMac has 2.x, 4 channels each w/~500MB/s which practically shows in native SSD benchmards upwards of 1500MB/s for the skylake refresh machines.

    My guess is that the new 3rd party SSDs can operate at much higher speeds, but would be limited by the iMac PCIe interface to 2.X speeds. If this is confirmed, that leaves only the connectivity question open: does it "fit" or not? :)
     
  12. Fl0r!an macrumors 6502a

    Joined:
    Aug 14, 2007
    #12
    You cannot put anything but an Apple SSD in the PCIe Slot.
     
  13. bogg macrumors 6502

    bogg

    Joined:
    Apr 12, 2005
    Location:
    Sweden
    #13
    Please note that the 500MB/s per lane for PCIE2.0 is raw bandwidth, consider it is using 10B8B encoding so the actual usable bandwidth is 80% of that (that is 400MB/s per lane) 4x400=1600MB/s, so the iMacs internal SSD pretty much maxes it out already.

    The easiest (and maybe only) way of upgrading it to SSD is to use the SATA connector for the harddrive, but then you are as said locked to about 550MB/s read/write. You could buy a 1TB SSD, connect it to the SATA-port and make a SSD+SSD Fusion drive to get 1.12TB of storage. Hoping that OS X is smart enough to realize the built in 128GB one is faster than the SATA-connected one :)
     
  14. Brian33 macrumors 6502a

    Joined:
    Apr 30, 2008
    Location:
    USA (Virginia)
    #14
    zerozoneice -- I happened to come across this, about Apple's support of NVMe:

    Q: Doesn’t Apple supply NVMe drivers and EFI boot ROMs for their new machines?

    A: Apple chose to make their NVMe devices and drivers non-compliant with the NVMe standard. Why they use the NVMe name for a non-compliant device and driver is a mystery.


    Someone has apparently come up with a driver that allows NVMe flash storage to work in the old Mac Pro or a PCIe expansion box with a new Mac Pro, but he specifically says that OS X will probably never be able to boot from it. http://www.macvidcards.com/nvme-faq.html

    It's a shame that it seems to rule out using a standard NVMe M.2 flash card in the Skylake iMacs...
     
  15. zerozoneice thread starter macrumors regular

    Joined:
    Jun 26, 2013
    #15
    ok, so this rules out a total swap and leaves us with the default apple ssd for boot&OS and probably a 3rd party SSD instead of the physical HDD, limited to around 500MB/s..i'd say much better than any HDD or SSHD around.
     
  16. Samuelsan2001 macrumors 603

    Joined:
    Oct 24, 2013
    #16
    Yeah thats still going to be a stupidly fast solution even if you set it up as a fusion drive.
     

Share This Page