boot from legacy usb drive to install windows efi


F

fabio8v

Well-known member
Local time
9:08 PM
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OS
w11/os catalina
hi
I have an old dell t3400, only legacy, till windows server 2022 was possible install in legacy mode but with 2025 no more, I remember that it was a boot manager, booting for legacy and then installed in efi mode, of course, at the end, I always need the usb pen to boot... is still possible?

P.S. The boot was by cd, maybe this is the right way
 

My Computer My Computer

At a glance

w11/os catalinai7 377016 gbnvidia 710 2gb
OS
w11/os catalina
Computer type
PC/Desktop
Manufacturer/Model
assembled
CPU
i7 3770
Motherboard
gigabyte b75m d2v
Memory
16 gb
Graphics Card(s)
nvidia 710 2gb
Sound Card
on board
Monitor(s) Displays
3 x samsung 24"
Screen Resolution
1920 x 1080
Hard Drives
2x ssd 1tb samsung
Here is how to install or upgrade Windows 11 version 25H2 on an unsupported PC.

 

My Computer My Computer

At a glance

Windows 11AMD Ryzen 7 5700GMicron Technology DDR4-3200 16GBNVIDIA GeForce RTX 3060
OS
Windows 11
Computer type
PC/Desktop
Manufacturer/Model
HP Pavilion
CPU
AMD Ryzen 7 5700G
Motherboard
Erica6
Memory
Micron Technology DDR4-3200 16GB
Graphics Card(s)
NVIDIA GeForce RTX 3060
Sound Card
Realtek ALC671
Monitor(s) Displays
Samsung SyncMaster U28E590
Screen Resolution
3840 x 2160
Hard Drives
SAMSUNG MZVLQ1T0HALB-000H1
fabio8v said:
I have an old dell t3400, only legacy, till windows server 2022 was possible install in legacy mode but with 2025 no more....
Click to expand...
Your T3400 will have an Intel Core 2 processor.

1786708336553.webp

The Core 2 does not have the SSE4.2 instruction set. This is a necessary and un bypassable requirement to be able to run 24H2 and above. The last version of Win11 your T3400 can run is 23H2.

Windows 11 24H2 has un-bypassable hardware requirements...

https://www.ghacks.net/2024/04/23/windows-11-24h2-wont-boot-if-the-pc-does-not-support-this-cpu-feature/ CPU "must" have SSE4.2 instruction set (RED box). This requirement can NOT be bypassed...
www.elevenforum.com www.elevenforum.com


Last time I checked (when 25H2 was released last October) for an unsupported device that has SSE4.2 the known install workarounds still worked.
Bree said:
With my 'least appropriate' laptop falling at the SSE4.2 hurdle testing duties fell to my 2nd most inappropriate laptop, a Toshiba L750 from 2011, a Legacy BIOS machine with no TPM and a Pentium B950.

I'm please to report that the known registry fixes from 24H2 still work with the new 25H2 install media. As I borrowed these from Rufus that should continue to work too.
Click to expand...
 

My Computers My Computers

System One System Two Other systems

  • At a glance

    Windows 11 HomeAMD Athlon Silver 3050U8GBRadeon Graphics
    OS
    Windows 11 Home
    Computer type
    Laptop
    Manufacturer/Model
    Acer Aspire 3 A315-23-R9VY
    CPU
    AMD Athlon Silver 3050U
    Memory
    8GB
    Graphics Card(s)
    Radeon Graphics
    Monitor(s) Displays
    laptop screen
    Screen Resolution
    1366x768 native resolution, up to 2560x1440 with Radeon Virtual Super Resolution
    Hard Drives
    1TB Samsung EVO 870 SSD (from April 2026: 250GB EVO 850)
    Internet Speed
    150 Mbps
    Browser
    Edge, Firefox
    Antivirus
    Defender
    Other Info
    UPDATE - 11 April 2026: due to lid hinges starting to break up this laptop has been retired from active duty. The OS with all software and files has been migrated to my System Seven in 'Other systems' to carry on as my general purpose 'main machine'.

    I've now clean installed 25H2 and used Garlin's scripts to update Secure Boot to CA 2023 and revoke the PCA 2011 certificates. It's new role is to test secure boot issues.

    Info for 2021-2026:
    fully 'Windows 11 ready' laptop. Windows 10 C: partition migrated from my old unsupported 'main machine' then upgraded to 11. A test migration ran Insider builds for 2 months. When 11 was released on 5th October 2021 it was re-imaged back to 10 and was offered the upgrade in Windows Update on 20th October. Windows Update offered the 22H2 Feature Update on 20th September 2022. It got the 23H2 Feature Update on 4th November 2023 through Windows Update, 24H2 on 3rd October 2024 through Windows Update by setting the Target Release Version for 24H2, and 25H2 on 30th September 2025 through Windows Update by setting the Target Release Version for 25H2.

  • At a glance

    Windows 11 ProIntel® Core™ i5-520M8GB(integrated graphics) Intel HD Graphics
    Operating System
    Windows 11 Pro
    Computer type
    Laptop
    Manufacturer/Model
    Dell Latitude E4310
    CPU
    Intel® Core™ i5-520M
    Motherboard
    0T6M8G
    Memory
    8GB
    Graphics card(s)
    (integrated graphics) Intel HD Graphics
    Screen Resolution
    1366x768
    Hard Drives
    500GB Crucial MX500 SSD
    Browser
    Firefox, Edge
    Antivirus
    Defender
    Other Info
    unsupported machine: Legacy bios, MBR, TPM 1.2, upgraded from W10 to W11 using W10/W11 hybrid install media workaround.

    In-place upgrade to 22H2 using ISO and a workaround.
    Feature Update to 23H2 by manually installing the Enablement Package.
    In-place upgrade to 24H2 using hybrid 23H2/24H2 install media.
    Upgraded to 25H2 by Enablement Package.

    Also running Insider Experimental 263xx and 29xxx builds and Windows 10 as native boot .vhdx.
  • My SYSTEM THREE is a Dell Latitude 5410, i7-10610U, 32GB RAM, 512GB NVMe ssd, supported device running Windows 11 Pro.

    My SYSTEM FOUR was a 2-in-1 convertible Lenovo Yoga 11e (1st gen) type 20DA, Celeron N2930, 8GB RAM, 256GB ssd. Unsupported device. This has now been sold. It has been replaced by my System Eight.

    My SYSTEM FIVE is a Dell Latitude 3190 2-in-1, Pentium Silver N5030, 8GB RAM, 1TB NVMe ssd, supported device running Windows 11 Pro, plus Insider Beta, Experimental 263xx and 29xxx builds (and a few others) as a native boot .vhdx.

    My SYSTEM SIX is a Dell Latitude 5550, Core Ultra 7 165H, 64GB RAM, 1TB NVMe SSD, supported device, Windows 11 Pro, Hyper-V host machine. Updated to 25H2 on 30th September 2025.

    My SYSTEM SEVEN is a Lenovo Thinkpad T580, 1920x1080 touchscreen, Intel Core i7-8650U, 16GB RAM, 512GB NVMe SSD + 2nd 512GB NVMe SSD, a supported device for Windows 11. This is my current general purpose 'main machine'. The installed Windows 11 Home from my System One has been migrated to this machine. As its new home has an existing digital licence for Pro I've been able to upgrade the migrated OS from Home to Pro.

    My SYSTEM EIGHT is a 2-in-1 convertible Lenovo Yoga 11e (5th gen) type 20LN, Celeron N4120, 8GB RAM, 512GB NVMe ssd, a supported device for Windows 11. Currently running Windows 11 Pro, plus Insider Beta, Experimental 263xx and 29xxx builds as native boot vhdx.
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