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How to install with an existing Windows 10 installation to dual boot?

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Hello. I have a desktop PC with Windows 10 and the following hardware:

ASUS P8P67LE
Intel Core i5 (2011)
8 GB of RAM
AMD Radeon HD 6790 graphics card

I'd like to install Mojave without wiping my existing Windows 10 installation, so I can dual boot, but I want to install Mojave in a different SSD drive than the one with Windows 10. So, how do I go about this? (if my hardware is suitable).

I'm sure there are already guides to do this, but I'm not sure how to install without wiping Windows 10 from my primary SSD. Any considerations I should have? What guide or guides are the ones I should follow for this task?

Thanks in advance for the help!
 
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Going Bald

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Purchase a SSD for Mac OS.
Install SSD.
Disconnect Win10 drive
Install Mac OS
Reconnect Win10 drive
Boot to BIOS and make the Mac OS drive first in drive boot order. Save&exit, continue boot.

Before you make your Mac OS USB installer, boot Win10. Open a command window and run msinfo32.
Look for whether BIOS Mode is Legacy or UEFI. When you use Unibeast to create the USB installer, select the correct BIOS Mode to match yours.
 
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Thanks for that answer @Going Bald. What about installing Mac OS in a HD with Windows 10 (UEFI)? Can I just resize it with GParted and install Mac in unallocated space?

I know how to deal with GRUB and Linux but not Mac OS. The SSD is mandatory? I'm not using SSD disk at this moment but I have 1 TB to split into more OS if I can do it.

That's OK?:
- Make an APFS partition with 200GB (for Mac OS).
- Download ISO and make USB.
- Boot and install, then apply patches from MultiBeast.

I'm also looking for the better choice to use as multi-boot selector regarding updates in Windows. Maybe Grub?
 
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Dual boot Windows/macOS by having both OS on the same drive is not recommendable. Windows won't be nice to your bootloader partition.

I recommend an UEFI setup of all operating systems you are intending to run. You need a second EFI-Bootpartition on another drive than that of windows to avoid having windows destroying this partition on every upgrade. Leave the windows drive alone. Install macOS with EFI on a second drive like "Going Bald" recommend, install CLOVER in that EFI partition as the bootloader. Make that Boot option the one the system boots from in your BIOS. CLOVER is able to boot anything: Windows, Linux, macOS. It will find and offer you all options available to boot automatically. It will find the EFI OS Manager of Windows on the other drive and more.

Edith means after having setup Multi-Boot Windows/macOS properly, you are still able to give macOS part of your original drive for storage.
 
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@higgins thanks!

So, there is no way to use both systems in same HD partitioned? Maybe disabling 'hard' updates or cloning boot-partition after that kind of updates?
 

Going Bald

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@higgins thanks!

So, there is no way to use both systems in same HD partitioned? Maybe disabling 'hard' updates or cloning boot-partition after that kind of updates?
boot Win10, open a command window as an adminstrator and run msinfo32.exe
 

Going Bald

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Sorry but I don't get it. I see 'System information'.
What you are looking for is the BIOS Mode. For an attempt to install Mac OS on same drive with Windows this must be UEFI mode.
Also, launch the Windows disk management utility and take a snapshot of the window and post it.
What you are looking for is the EFI partition. Does it exist? What size is it? It needs to be at least 200MB and best if it is the first partition on the Windows drive.
 
Joined
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Dell 05NVNV
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i6-6500U
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Radeon R5 M335
What you are looking for is the BIOS Mode. For an attempt to install Mac OS on same drive with Windows this must be UEFI mode.
Also, launch the Windows disk management utility and take a snapshot of the window and post it.
What you are looking for is the EFI partition. Does it exist? What size is it? It needs to be at least 200MB and best if it is the first partition on the Windows drive.
I'm in UEFI BIOS mode (EFI with 200 MB at first).
 

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Going Bald

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Mount the EFI partition and take a screenshot of the contents and post.

So far, looks like a good candidate, but would be better if you could shrink the system partition a bit more to give you 50GB of unallocated space to use for Mac OS.
 
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