Previous 1 2 Next 26 Replies Latest reply: Aug 12, 2013 4:04 AM by Contradel
_z_ Level 1 (0 points)

Hi, everyone.  After a two-year wait, I'm ready to buy my first iMac (was waiting for USB 3.0).  Before I get into my questions, I'll give you an overview of where I'm coming from so we can keep the discussion focused.


My Usage

I'm buying an Apple computer because it is the best-looking, quietist, and most powerful all-in-one computer I can find right now, but Windows is still my preferred operating system.  I've used OS X before – it looks great and I'm sure it works great for a large number of people, but it's not for me.  Windows works well and efficiently for me and I have thousands of dollars of design software for Windows.  I'm not interested in a virtualization solution because of my performance needs.  However, I do want to keep the OS X installation, if possible, for website testing and to play around with to learn the operating system better.


What I Want

I was attempting to buy the Late 2012 iMac last weekend, but it appears the BootCamp specifications and the Fusion Drive are currently limiting my usage needs.  I'm configuring the top model iMac with the i7-3770 processor, 24GB RAM (8 default + 16 from Crucial), GTX 680MX, and the 3TB Fusion Drive.  I don't actually want to use the Fusion Drive, though.  I want Windows 7 64-bit and OS X 10.8 installed on the 128GB SSD and to use the 3TB hard drive as storage for my music, videos, photos, and documents.


My Questions

1.  I've found a bunch of posts regarding installing Windows on the Fusion Drive, but they all seem to be about putting Windows on the slower 3TB hard drive portion and/or about trying to keep the Fusion setup after installing Windows.  Does anyone have a walk-through for a new Mac user on how to break the Fusion Drive configuration and install Windows 7 and preferably OS X on just the SSD?


2.  I've seen a bunch of posts debating about whether Windows can be installed natively using EFI to bypass the BootCamp limitations.  Is this possible?  The 21.5" version is running EFI version 2.0, so I can only assume the 27" would too, but it's not been added on the Apple website yet (  From what I understand, Windows requires at least version 2.0 to run in EFI mode.  Also, if I am able to get this method to work, will I still be able to install the Windows drivers from the OS X installation USB (or do they even come with USB drives anymore?)?


3.  If I have to use BootCamp, I assume I will have to split the 3TB drive into 1TB and 2TB partitions for BootCamp to see it (so Windows can see it).  So I'd have Windows 7 and OS X on the SSD, and two storage partitions on the 3TB HDD that would show up as two drives for my files that both operating systems could access.  Is this assumption correct?


4.  I've seen posts about OS X automatically trying to rebuild the Fusion Drive.  Let's say I'm able to get Windows installed on the SSD.  Will OS X, or future updates to it, ruin my Windows installation?  I would hate to do all this work and then have an Apple update corrupt everything.



I know this is a long post, but I don't want to spend over $3,000 until I can be sure I can make it work for me.  Thanks to anyone who can help!

iMac, Windows 7

iMac, Windows 7
  • mende1 Level 10 (92,186 points)

    First, an advice: Boot Camp isn't compatible with 3 TB hard disks and Fusion Drive. For 3 TB hard disks, there's a workaround, but it doesn't work on a 3 TB Fusion Drive, so you won't be able to install Windows until Apple fixes this, so my advice is to wait until Apple launches OS X 10.8.3 or buy the iMac with a 1 or 2 TB hard disk and an external disk.


    1. The SSD is used automatically by OS X to store the applications and data you most use, but Windows can't use it, and there's no workaround for this.


    2. You can try to install Windows 8 in EFI mode, but I don't guarantee that it works. I tried it on my iMac and I started getting BSODs after some startups. Also, Macs don't use UEFI 2.0 (Macs use EFI 1.x), so you can't use Windows 8 advanced features such as Secure Boot. For Windows 7, you can't install it in EFI mode (it requires UEFI 2.0 or later)


    3. Fusion Drive only allows you to have two volumes, and with Boot Camp, you can only have two volumes on your computer: one for OS X and the other one for Windows. That's because Boot Camp emulates a BIOS to make Windows run (although it isn't neccesary in Windows 8, if Apple would want).


    4. First, you can't install Windows on the SSD. Then, OS X shouldn't ruin Windows because each operating system have got its space

  • Kappy Level 10 (265,914 points)

    If this was a requirement for you prior to purchase, then why did you even opt for the Fusion Drive?

  • _z_ Level 1 (0 points)



    My preference is not to use BootCamp.  I'm reposting here because I was told that this is the forum where I would most likely find people who can help me out.


    Why do you say that the Late 2012 27" iMac doesn't use EFI 2.0?  According to this page (, the Late 2012 21.5" iMac supports 2.0, so why wouldn't the 27" version support it?  Windows has supported EFI 2.0 and up since at least Windows 7 (and maybe Vista?), so why wouldn't that work?  Like I said, I've seen it debated, but that largely rested on people presuppsing that Macs weren't using EFI version 2.0.


    I don't want to use the Fusion Drive.  I want to disable it and just use the SSD for my OS installs and the 3TB hard drive for storage.

  • _z_ Level 1 (0 points)



    If there was a non-Fusion Drive version that gave me an SSD and a 3TB hard drive, I would certainly do that.  But it's not an offering.

  • mende1 Level 10 (92,186 points)

    Apple has named it EFI 2.0, but that's compared to other Macs EFI. In conclusion, it doesn't indicate that it's using UEFI 2.0, and it's not using UEFI 2.0.


    You can't disable Fusion Drive. OS X creates it by default when you have flash storage and a HDD installed, so you will have to remove the SSD or HDD from the Mac and void the warranty. In this case, the thing I recommend you to do is to buy the iMac only with flash storage and buy an external disk to save your files

  • _z_ Level 1 (0 points)



    I've found a number of posts that show that the Fusion Drive can, in fact be disabled.  And I've found other posts where people went on to install Windows on the 3TB drive and rebuild the Fusion Drive to work.  I only want to do part of that.  I just want to disable Fusion drive and then install on the SSD, which should be easier, but I can't find any instructions for it.  On the Apple page I link to, it lists the Apple version and then the EFI version in parenthesis after it.

  • mende1 Level 10 (92,186 points)

    Can you give me a link to a how-to about disabling Fusion Drive?


    I think you haven't understood my explaination about EFI versions. Macs use EFI 1.x, but Apple has got a different EFI version for each Mac, and that's why for the new iMac, Apple has listed it as 2.0, but it doesn't mean that they have upgraded to UEFI 2.0. Apple doesn't use the UEFI version that PCs use, because Apple uses EFI (it's like UEFI, but older)

  • Kappy Level 10 (265,914 points)

    Your iMac comes with a special version of Disk Utility. Did you see if it would enable you to separate the SSD and HDD?


    I would suggest a Google search on "fusion drive." There are numerous articles on how to create your own that explain how you make one and how you can likewise separate the drives. You may well find your solution in one of those articles.


    I disagree with Mende1 that you can't disable it. But it's a matter of knowing what to do.

  • Allan Eckert Level 9 (50,709 points)

    OK. If you have found other posts where people have done this then follow their directions.


    We are only tell you what we know here and that is you can't do it.



  • _z_ Level 1 (0 points)
  • mende1 Level 10 (92,186 points)

    Thanks. I didn't know that it was a way to disable Fusion Drive

  • _z_ Level 1 (0 points)



    I have found other posts doing part of what I want, but no clear instructions for a new user and not doing exactly what I'm wanting to do.  I think my configuration would be desirable by a great number of people, but maybe not.  I was hoping other people here would be able to help me out with that.

  • _z_ Level 1 (0 points)



    Is there a way to tell what version of EFI a Mac is using?  If so, maybe one of the few people that has a Late 2012 27" iMac already can tell us.

  • _z_ Level 1 (0 points)

    Can anyone else help with this, perhaps?

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