- Most UEFI systems will be able to boot only x64 boot media in UEFI mode as here
- With customized ISOs, it will always be experimental and may support one or the other.
- Normally, UEFI boot needs a FAT32 format drive or such partition on the boot drive. But FAT32 can only support files that are less than or equal to 4GB. So, the Isos, which are having files ( extracted ) larger than 4GB, has to be applied to the boot media with some tricks.
- SLaks way will be possible only as long as the biggest file (normally
install.wim) is lesser or equal to 4GB because it uses single FAT32 partition on the boot drive.
- Rufus uses a single FAT32 partition when the biggest file is under or equal to 4GB otherwise, you will only have NTFS as an option with UEFI + GPT. That way, you will need to disable Secure Boot in the UEFI firmware to boot into the media. Once Installation or Repair is complete, you can again turn Secure Boot On, but Secure Boot disabling/enabling is not very straight forward in all UEFI firmware such as some Asus Motherboards
Methods: (assumes the largest file is less than 4 GB)
(A) SLaks way
- Download the required ISO : Win 8/8.1/10 / Win 7
- Extract the ISO to a folder with a good archiver, such as7zip / WinRAR
- Insert the pen drive & format it as FAT32
- Copy all the files from the extracted ISO folder to the root of the pen drive
- The drive is ready to boot from (will be bootable in both UEFI & MBR)
(While working with ISOs with
.swm files, this way, they always booted in both UEFI & MBR)
(B) Rufus Way
- Insert the pen drive
- Launch Rufus & follow the below image and instructions:
- *Drive will be formatted, so back up any important data on it*
- Select the pen drive in the Device menu
- Click SELECT, browse to the Win 7/8/8.1/10 iso and double click it
- It will show under Boot selection (marked as blue in the
- Choose Partition scheme as GPT & Target system as UEFI
- Press START
- Once it shows READY, it's done, and you can close Rufus
Methods: (assume largest file > 4GB)
Do you have a file(s) larger than 4GB?
When the largest file(s) is / are greater than 4GB,
SLaks way will prompt you with something like 'the file size is not suitable for ...'
Rufus will give you no option of FAT32 against UEFI + GPT, leaving only NTFS to go with!
(Obviously, these methods will also work when the largest file(s) is / are smaller or equal to 4GB!)
(A) Rufus: Go with UEFI + GPT + NTFS & Disable Secure Boot to boot into the media!
(B) Change & Replace the
.wim file to
.esd file & use the SLaks way.
There are many ways to do that like DISM++
(But I won't suggest that because that process takes up a lot of resources. If your system is not powerful enough, It will substantially paralyze your system!)
(C) Split & replace
.wim file to multiple
.swm files which should be smaller than 4GB individually!
I found that only one file was over 4GB in the ISO which was
install.wim. All other files &
boot.wim was well under 4GB. So, we have to split & replace
We will use : wimlib-imagex
The general command is :
wimlib-imagex split --check windows.wim windows.swm 100
We want to split
install.wim in 1200MB
So, the general command for us :
wimlib-imagex split --check install.wim install.swm 1200
we will need to tell path(s) for everything wherever needed.
For a practical eg.:
Extract the windows iso to a folder with an archiver: 7zip / WinRAR
Make 3 folders in the
c: root i.e.:
c:\New 1 ,
c:\New 2 &
Extract the downloaded wimlib zip file to the root of the New 1 folder.
In the extracted iso folder, navigate to Sources folder. Drag & drop
.install.wim to New 2 folder.
Open a command prompt.
Copy, Paste & Run this command as it is (with quotes!):
"c:\New 1\wimlib-imagex" split --check "c:\New 2\install.wim" "c:\New 3\install.swm" 1200
Wait for the things to finish.
Exit command prompt.
install.swm files are ready in
Navigate to the extracted iso folder & Replace
Format the pen drive with FAT32.
Drag & drop the Iso extracted folder ( in which we have replaced install.wim with install.swm files ), to the pen drive & let it finish.
(This way the pen drive will be bootable into both UEFI & MBR)