Upgrading Win 8.1/Mavericks to Win 10/El Capitan

[Phase-1]

Hello-

I don't like having to post questions, but after a couple of days of searching around and many reboots, here it goes...

History:

• I have a Gigabyte H77N-WiFi motherboard with HD Graphics 4000. Mavericks thinks it's a (whoa, it used to say Mac Pro, now it's saying "Mac mini Server Late 2012").
• I have two SSDs:
  • Win 8.1 Pro/NTFS
  • Mac OS X (Mac OS Extended (Journaled))
• Installed Win 8.1 Pro and Mountain Lion successfully with Chameleon
  • My motherboard is EUFI, but I can't remember if I installed via EUFI or Legacy. I suspect Legacy because my Windows drive has as "System Reserved" partition and not an "EFI" partition.
• Upgraded from Mountain Lion to Mavericks (no issues)
• Added GeForce 950 video card, was never able to boot to Mavericks again, but Windows still worked great
• Finally had a spare weekend to work on this, removed GeForce 950, reset motherboard CMOS and booted into Mavericks
  • I don't remember all the EUFI settings that worked prior to the CMOS reset -- XMP being one.
• Learned that GeForce 950 requires Yosemite and my motherboard prevents upgrade to Sierra
• Obtained El Capitan and used UniBeast 6.2 to create a bootable installer on a 16 GB USB drive (in a USB 2 port), carefully following the guide on tonymacx86.com
  • I've tried both EUFI and Legacy many times. I noticed that when I create an EUFI installer, the /EFI directory exists, but after I try booting with that USB installer and fail, booting back into Mavericks shows a /EFI-Backups directory, but no more /EFI directory.

Present:

• I've tried many combinations of:
  • EUFI/Legacy installer
  • EUFI/Legacy booting (via EUFI settings)
  • XMP/No Extreme Memory Profile
• My bootloader IS now Clover
• Currently using Intel graphics (GeForce 950 was removed)
• I can still boot into Mavericks via Clover (EUFI boot)
  
• I can still boot into Windows by changing the boot drive (Legacy boot)
  
• I can't boot off the USB to install El Capitan
  • With EUFI Installer (I don't have the exact details, will probably include in followup post):
    
    • error loading kernel cache (0x9)
    • error allocating ___ pages at ___ alloc type 2
    • rebooting in 10 seconds
  • With Legacy Installer (I don't have the exact details, will probably include in followup post):
    • Using reloc block in__
    • ++++++++++++++
• No boot options have been set
  • Side note: when I try to type "nv_disable=1" in Boot Args, when I type the underscore (_), I instantly get 1- or 2- dozen underscores instead, and editing that line is very difficult when this happens, so I resort to having no options set.

Help:

• Right now, I just want to upgrade Mavericks to El Capitan, but I'm stuck with the installer. Can anyone help?
• Future Direction:
  
  • Would love to dual-boot Windows 10/El Capitan with GeForce 950 and using my 4K monitor in both systems.
  • Would also love to be able to use Hyper-V (from the Windows side) to set up VM's as I'm a Windows developer

Thank you. Hopefully there's enough info here for someone to pick up on where my problem lies.

 

[Going Bald]

There is a very simple solution for your problem. First, make sure your BIOS is UEFI capable. If it is not, check OEM board site support for upgraded BIOS. IIRC, most 7 series boards came with UEFI capable BIOS.
There are several methods to convert an active MBR Windows drive to GPT without destroying the installation in the process. You could try one of them if you want.

Or, you can do it the hard (best) way.
Make sure any 3rd party apps for Win8.1 will work with Win10 and make sure you have the installation media to re-install them.
Create a Win10 UEFI installer USB. You will use it later. I really recommend you purchase a Samsumg 850 EVO as it comes with the software to clone your Windows drive, just in case.
Disconnect the OS X SSD. Backup - BACKUP - BACKUP your Windows documents/videos/music/etc. folders and your saved files to off line media. If it is not important enough to back it up, then it does not matter if you lose it in this process.
Upgrade the Win8.1 SSD to Win10. This gets you Win10 license code in the UEFI of the board.
Boot the Win10 installer UEFI mode (use the function hot key to select a boot device - Win10 USB shows as USB and UEFI USB - select the UEFI USB. At the first screen, select custom install - at the next screen select each partition and delete it until you have only free space left. Click on Actions - convert GPT. Then click on install and let it do its thing.

You could also use shift+F10 to open a command prompt and use diskpart to clean and convert the drive to GPT - this is my method, but I do not know how savvy you are with diskpart.

Once Win10 has installed, restore your files, re-install your 3rd party apps and you are good to go.

You might take a look at the pinned guides in the MultiBooting forum.

 

[Phase-1]

Thanks for your response.

First, make sure your BIOS is UEFI capable.

Yes, my motherboard firmware is UEFI.

Create a Win10 UEFI installer USB

Don't know offhand how to do that, but I'll find out.

I really recommend you purchase a Samsung 850 EVO as it comes with the software to clone your Windows drive, just in case.

Thanks for the advice; was going to purchase https://www.terabyteunlimited.com/image-for-windows.htm anyway, so will likely use that instead.

You could also use shift+F10 to open a command prompt and use diskpart to clean and convert the drive to GPT - this is my method, but I do not know how savvy you are with diskpart.

I'm more of a Windows guy than MacOS; I've used diskpart before.
You're suggesting that I can use diskpart to change the partition type of the drive non-destructively? If so, what should I do about the System Reserved partition -- is that included in "select each partition and delete it" per your instructions?

Thanks again for your helpful response. It may be a few days before I can respond with my results, but I'll post them when I can.

 

[Going Bald]

I'm more of a Windows guy than MacOS; I've used diskpart before.
You're suggesting that I can use diskpart to change the partition type of the drive non-destructively? If so, what should I do about the System Reserved partition -- is that included in "select each partition and delete it" per your instructions?

Use diskpart only if you want to destructively wipe clean the drive. Also, the Windows 10 disk management tool can only convert MBR to GPT if there are no partitions on the drive, so it is also destructive.
See http://thewindowsclub.com/convert-mbr-to-gpt-disk