Windows installed without a USB installer connected to my system

One "magic" installation when the files isn't on disk or USB.. PXE boot.
But i never heard of "normal" people use that thogh.... Nerds and company's yes......
or a really odd never heard of OEM recovery solution.

garlin said:

If this PC has a MSI motherboard, there won't be an OEM recovery partition and to my knowledge, MSI doesn't provide a vendor tool to create a recovery USB image or make a factory recovery partition for you.

Click to expand...

True.

garlin said:

@Wannagofast's theory makes the most sense. At some point, a Windows install or recovery USB drive started the install or recovery process. Typically this involves extracting an install image to a mounted filesystem. When finished, Setup runs bcdboot to prepare the BIOS to boot into the freshly extracted Windows to continue the rest of the install.

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Possibly. I can't say one way or the other.

garlin said:

Assuming there was a corrupted BCD store or bad BIOS settings, then it can't find the boot manager. After clearing up the problem, BIOS detects there's a valid EFI volume with a working boot manager. So it boots into the unfinished Windows and continues processing.

Click to expand...

Possibly. When I last tried to boot into the UEFI installer, the boot order section of the BIOS detected only the UEFI USB drive, nothing else. Earlier on, the boot order also detected the Windows (something) manager. I just don't remember, it's been too many crash-and-burn cycles.

garlin said:

The question would have been AT THE TIME, what version of Windows was installed? Not what version it may have ended up, because Windows Update would have patched the system. If you knew the exact Windows version it would rule out different possibilities as to where it came from.

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It was 26100.6000 something. Now it's 26200.8457.

garlin said:

A too recent initial Windows build would rule out something left over from when the PC was purchased.
A too old initial Windows build would rule a recent recovery image that was built.

Click to expand...

This motherboard was purchased and installed at the end of March. The BIOS was dated Jan 26, 2026

In other words I didn't capture all the information, including all my various install attempt steps, that would have pointed to a definitive explanation. I should fault myself for not keeping detailed work logs.

Marie SWE said:

One "magic" installation when the files isn't on disk or USB.. PXE boot.
But i never heard of "normal" people use that thogh.... Nerds and company's yes......
or a really odd never heard of OEM recovery solution.

Click to expand...

MS publishes a guide for OEM's on creating a recovery partition, and preparing it for a "push button reset". I believe Lenovo may support this feature.

You take a fresh PC straight from the factory, user logs on and the vendor usually instructs them "build a recovery image right now". A tool then captures the current Windows (because it's relatively new and clean, not messed up by the user) to WIM/ESD file and carves out a new recovery volume at the tail of end of the drive.

The tool throws in the recovery image, and along with some helper files so it's essentially the same as an USB recovery drive but buried in a separate partition. Finally the tool creates a custom BCD entry for recovery, and when the user screws up their system (and it's not a HW failure), they pick the OEM recovery option and the boot entry starts from the recovery volume.

Whole point behind this is you don't ask the user to go find a spare USB drive, because you're stealing space on the system disk and maybe they won't notice that disk space is gone. The bad part is it doesn't help if you lose the system drive to HW failure or something trashes the disk data. Keeping it on an external USB drive would be better in terms of protection.

But yeah, such a creature exists (for some systems). A lot of this was started in response to "why don't I get a recovery DVD with my PC like I used to back in the 90's?".

PhilB said:

It was 26100.6000 something. Now it's 26200.8457.

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6000 something puts you from Sep 2025 to Oct 2025. I dunno if that rings any bells.

garlin said:

MS publishes a guide for OEM's on creating a recovery partition, and preparing it for a "push button reset". I believe Lenovo may support this feature.

But yeah, such a creature exists (for some systems). A lot of this was started in response to "why don't I get a recovery DVD with my PC like I used to back in the 90's?".

Click to expand...

Cool, i didn't know that one.. But it sounds as a user friendly solution with push button reset..... but wait.. now when you mention it.. i do have one of those buttons on my Lenovo Y520... i think i also have one of those on my MSI laptop...
But they run Linux with swapped drives.. so i have a feeling that button is dead unless they have a hidden chip with the install files on the motherboard.

I miss those old days when you got either a recovery DVD or five CD's.... or on first boot you got the question to burn a recovery DVD.

If you emptied the drive inside Windows, most likely through Computer Management -> Disk Manager, then it won't allow you to delete the recovery partition. You need to use Diskpart (command line tool) to do that, or a third-party disk manager, such as Minitool Partition Manager. I am not sure, but I think it doesn't allow you to do that, even if you connect the disk as a second disk. However, if you boot into Windows 11 Setup and see the disk partition (probably in classic Setup, I didn't manage to see it in modern Setup), then it allows you to delete all partitions, including the recovery partition and then install Windows.

Marie SWE said:

Cool, i didn't know that one.. But it sounds as a user friendly solution with push button reset..... but wait.. now when you mention it.. i do have one of those buttons on my Lenovo Y520... i think i also have one of those on my MSI laptop...
But they run Linux with swapped drives.. so i have a feeling that button is dead unless they have a hidden chip with the install files on the motherboard.

I miss those old days when you got either a recovery DVD of five CD's.... or on first boot you got the question to burn a recovery DVD.

Click to expand...

I don't know if this is true for all systems, but in some it is F10 to boot into Recovery mode (reinstall Windows). Of course, it asks for confirmation before proceeding, so don't worry if you press that by accident while booting. Personally I prefer to keep a DVD or USB flash drive with the latest Windows 11 version, rather than rely on an outdated Recovery partition when disaster strikes. So I always delete the Recovery partition when I clean install Windows to get the maximum capacity of the disk. As you know, no matter how large is your disk, it is a matter of time before it is not enough. So why waste valuable disk space with a useless Recovery partition?

spapakons said:

I don't know if this is true for all systems, but in some it is F10 to boot into Recovery mode (reinstall Windows). Of course, it asks for confirmation before proceeding, so don't worry if you press that by accident while booting.

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I'm not so worried.. First of all.. those buttons is "hidden" like on routers etc, so you have to use a pen or something to press the button. and i have disk images of all my system drives in case of hardware failure. as i hate install OS's, you have to have a backup plan of the backup plan.

As I have said elsewhere, I have too much data to backup and too many apps and games to reinstall and reconfigure. So I avoid a clean installation as much as possible. If it is a minor issue, I can live with it. I only do a clean installation when there is absolutely no fix for a problem or when I feel it will take more time to diagnose and solve it than reinstalling Windows. I also upgrade from one version to the next.

"Small" upgrade scenario: Windows 7 64-bit upgraded to Windows 10 64-bit, upgraded to many higher Windows 10 64-bit versions and finally to Windows 11 21H1, 22H2... all the way to Windows 11 25H2.

"Crazy" upgrade scenario, to make sure I am not missing anything: Windows XP x64 SP2, add Plus! for Windows XP, add Plus! DME for Windows XP. Then upgrade to Vista 64-bit, add SP1, SP2, then upgrade to Windows 7 64-bit, add SP1, upgrade to Windows 8.0 64-bit, then to 8.1 64-bit, upgrade to Windows 10 64-bit, do some upgrades to reach version Windows 10 22H2 64-bit, then upgrade to Windows 11 21H2, 22H2, 23H2, 24H2 and finally to 25H2. No, I haven't actually done it, just kidding... But I have done Windows 95, add Plus! 95, upgrade to 98, add Plus! 98, upgrade to ME and finally to XP, to have all the screensavers, wallpapers and Plus! games!

spapakons said:

"Crazy" upgrade scenario

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I have actually never in my entire computer life from 1987 upgraded from one OS to a newer.. not in windows, not in Linux.. I have always done clean installs.

Thankfully, I found a way not to miss anything. I can copy all wallpapers for the respective Windows versions running in a virtual machine into Windows 11. I can also copy most screensavers, but those of Windows 98 Plus! unfortunately don't work properly on modern Windows due to DirectX incompatibilities. If I want the games, I can trick Plus! 98 to install on Windows 11 and I can also install Plus! for XP and Plus! DME for XP in Windows 11. Or find third-party equivalent games.

spapakons said:

If you emptied the drive inside Windows, most likely through Computer Management -> Disk Manager, then it won't allow you to delete the recovery partition. You need to use Diskpart (command line tool) to do that, or a third-party disk manager, such as Minitool Partition Manager. I am not sure, but I think it doesn't allow you to do that, even if you connect the disk as a second disk. However, if you boot into Windows 11 Setup and see the disk partition (probably in classic Setup, I didn't manage to see it in modern Setup), then it allows you to delete all partitions, including the recovery partition and then install Windows.

Click to expand...

That sounds like a very plausible explanation.

garlin said:

6000 something puts you from Sep 2025 to Oct 2025. I dunno if that rings any bells.

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I just double-checked using the CMD ver command. 26200.8655

That's right now. Presumably you didn't block WU and the PC updated itself since you first logged on.

garlin said:

That's right now. Presumably you didn't block WU and the PC updated itself since you first logged on.

Click to expand...

Maybe, but I missed that. My digital license is active. Same system as before, except new motherboard and CPU. Most of the old drives active. No new drives. And age and marital status unchanged.

I too run build 8655 (latest release, not Insider's). I see no issues so far, thanks God.