We were unable to create a partition or locate a partition.

Start on it, and tell me what happens. Don't restart when it freezes.

Well, I press a button to boot from the Windows installation, then I insert my key, etc... and when I have to choose the hard drive on which I want to install, I select it, proceed, and I get the error message: "We couldn't create a new partition or locate an existing partition."

And if I choose my other hard drive (the main one where W8 is installed), it tells me that my disk is in MBR and it needs to be in GPT.

You don't know?

First, you need to do what I told you above... when you have your error message. Press left shift + f10, which opens the command prompt...

diskpart
select disk 0
detail disk
list partition
exit

And you should already set aside the hard drive with W8 32-bit, just to preserve it.

Thank you, it also helped me understand my issue!

Thank you ikewdu!

I have the same problem as you; it is certain that you have two or three physical hard drives plugged into your motherboard. The issue is that the default configuration of your motherboard has one of the hard drives set as the primary, and the others are considered secondary devices, like an external device such as a flash drive and the mouse. The solution is simple: you need to enter the motherboard configuration and go to
1. Advanced BIOS Features.
2. Hard Disk Drive.
Select the drive you want to set as the primary one, the one that you don't want to format, enable it, save the configuration, and you'll see that it will work fine afterwards, and you can install Windows 8 or Windows 10 without any issues.

Hello, I have the same problem and I have also tried the same commands but Windows still won't install.