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Is it safe to remove Dual Boot?

Anonymous
2025-06-09T14:57:23+00:00

Hi everyone,

Before I give myself another round of a headache, I want to make sure it's safe to do, so.

Recently I had to reinstall my Windows10. The new system went to my new SSD, while I have the old one (after a system reset, keys and mouse not working so I got rid of it) on my old SSD. When turning on my PC, gives me the screen to choose which Windows I'd like to boot. I choose the new one, and boots as should.

After the fresh install, I changed the Boot order, to the New SSD be the first option, but with that I got the error message of can't boot (press enter or F8). My question is, is it safe to delete the old Windows from msconfig-->Boot (the new windows is already the default option), or should I take precautions, and if yes, which ones?

*I (technically) moved every file I need, so I could format the drive in order to use it for system backup. But first I want to make sure it's safe to do so.

Thanks in advance.

Matyas

Windows for home | Windows 10 | Windows update

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  1. EmilyS726 230.9K Reputation points Independent Advisor
    2025-06-09T17:57:27+00:00

    Ah, sorry!! EFI won't work on MBR, it is for GPT only. Needs to adjust the commmands

    diskpart

    list disk

    select disk #

    list partition

    create partition primary size=500

    format fs=ntfs quick label="System Reserved"

    active

    assign letter=S

    exit

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  1. Anonymous
    2025-06-09T16:29:59+00:00

    You mean, diskmgmt.msc?

    I see this here. Please note that Drive D is my previous C with my old (and heavily corrupted) windows installation (long story short, wasn't able to make my new SSD visible and tried something out of desperation which resulted in Inaccessible Boot Device error, which I could restore, but after that my keyboard and mouse "refused" to work on login screen (normal and safe mode as well), but in bios and CMD worked fine, so I decided to, instead of experimenting further, do a fresh install on my new SSD).

    They are currently have the following Sata connection: Drive D: Sata0, Drive E: Sata1, Drive C: Sata3. I plan to rearrange them once I made sure that the New SSD able to boot windows.

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  2. EmilyS726 230.9K Reputation points Independent Advisor
    2025-06-09T16:23:22+00:00

    Yes, I didn't suggest that route, but it sounds like you are quite tech savvy.

    Do you need the instruction?

    If you do, Can you first go to Disk Management and share a screenshot first?

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  3. Anonymous
    2025-06-09T16:01:51+00:00

    I had a hunch that this would be the issue. To be honest, I don't want to do another round of clean install (since I imported almost everything already). Could the cmd-->diskpart work here, to build the boot table?

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  4. EmilyS726 230.9K Reputation points Independent Advisor
    2025-06-09T15:43:39+00:00

    Hello,

    It is safe to remove the old Windows, BUT that's ONLY when your new Windows installation is fully independent.

    You said Windows wouldn't boot when you change the boot order to the new SSD. That means your boot partition still lives on the old disk.

    Think of the boot partition like an index file. When the computer turns on, it needs to check there first to see how many Windows you have. When you did the clean install on your SSD, you made a mistake for not physically removing the old disk, hence the boot partition wouldn't be recreated in SSD, instead, it simply adds a new Windows reference in the existing boot partition in the old disk. This is why, when you change the boot order to the new SSD, it couldn't find the boot partition, and hit the error.

    To address this issue, it is probably quickest and easiest to just do another round of clean install on the new SSD while the old disk is physically removed for this process.

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