Partition issues

Hello,

New, nothing on it otherwise, copy your data aside and start from scratch.

Basically:

> UEFI mode (just that, nothing else, no legacy or anything)

> Reinstall if the disk where Windows is also in MBR
(4 TB HDD disconnected beforehand)

You start with a "custom" installation
You will follow the procedure and when you reach a table that lists the locations and asks you "where to install Windows".

At that moment:

Press the Shift and F10 keys
(the command prompt opens)
Enter the following commands one by one, confirming with enter:
diskpart
list disk
sel disk X (x should be replaced with the number corresponding to the hard drive you want to erase)
clean
convert gpt
exit
exit

Result -
In short, we empty the disk, convert it to GPT and then you return to the installation table.
You will only have one volume that you choose to install on.

> Once correctly installed, reconnect the 4 TB data disk
Open a command prompt (admin)
(= powershell admin, which you can access by right-clicking the start menu)

And redo the same commands given previously.
(of course, pay attention to the correct number, it's no longer the same disk we're touching)

----------
I almost forgot, your 4 TB once converted to GPT will likely not be visible, only present in disk management.
Just right-click on the graphical volume and choose "create simple volume"
And that's it, it will be visible.

After that, you can create as many partitions as you want... 1 or 2 or 50.

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You mean I could switch from MBR to GPT using a bootable USB? I already have one with Windows 10. But I already tried reinstalling and it tells me that I can't install on that drive because it's not GPT. It's frustrating.

Hello
No, these are ISO files to create either a CD/DVD or a bootable USB stick to start the PC and intervene on a disk, such as changing the disk mode from MBR to GPT, but not only!!
It's for making a LiveCD (bootable CD with a standalone system) very useful...
See you!
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Hello
By booting your PC with a Live CD like GParted, you can convert from MBR to GPT without data loss. (still make a backup just in case ;-).
But there are other Live CDs like Easeus, which you can search for on the internet.
See you later
If this answer helped or solved your issue: a little thank you, if it's resolved: click the green button at the top ;-)

Let the first one who has never opened a user manual throw the first mouse at me.

You didn't take an SSD to install the system, so you have one solution left: reinstall Windows. Boot into the BIOS to switch to UEFI mode. Start from your Windows installation media (USB or DVD). Delete the volume(s) and then install.

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