学校买了微软正版软件。新电脑只支持UEFI，而UEFI只能用FAT32格式启动U盘，FAT32无法存储大于4G文件，而win10的install.wim大于4G。花了很多时间没找到解决办法。

其实很简单，不需要UltraISO，也不需要Rufus，什么都不需要。只需要按照微软官方网站的操作说明执行即可。（https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/install-windows-from-a-usb-flash-drive ）

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Install Windows from a USB Flash Drive

What you need

Windows 10 install .iso

USB flash drive with at least 5GB free space. This drive will be formatted, so make sure it doesn't have any important files on it.

Step 1 - Format the drive and set the primary partition as active

Connect the USB flash drive to your technician PC.

Open Disk Management: Right-click on Start and choose Disk Management.

Format the partition: Right-click the USB drive partition and choose Format. Select the FAT32 file system to be able to boot either BIOS-based or UEFI-based PCs.

Set the partition as active: Right-click the USB drive partition and click Mark Partition as Active.

If Mark Partition as Active isn't available, you can instead use diskpart to select the partition and mark it active.

Step 2 - Copy Windows Setup to the USB flash drive

Use File Explorer to copy and paste the entire contents of the Windows product DVD or ISO to the USB flash drive.

Step 3 - Install Windows to the new PC

If your Windows image is larger than 4GB

Windows USB install drives are formatted as FAT32, which has a 4GB filesize limit. If your image is larger than the filesize limit:

Copy everything except the Windows image file (sources\install.wim) to the USB drive (either drag and drop, or use this command, where D: is the mounted ISO and E: is the USB flash drive.)

Dism /Split-Image /ImageFile:D:\sources\install.wim /SWMFile:E:\sources\install.swm /FileSize:3800

Note, Windows Setup automatically installs from this file, so long as you name it install.swm.

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