Install Windows From External Hard Drive [better] -

diskpart list disk (find your external drive – be careful not to pick the wrong one ) select disk 2 (for example) list partition select partition 1 active exit

You open Command Prompt as Administrator . install windows from external hard drive

Then you use bootsect /nt60 F: (where F: is your external drive) to write the Windows boot code onto it. diskpart list disk (find your external drive –

You plug the external hard drive into a working computer. It’s 500 GB, mostly empty. You know Windows setup won’t need all that space, but the drive has to be bootable. It’s 500 GB, mostly empty

Some older computers won’t boot from an external hard drive via USB. And if your external drive is slow (5400 RPM), the initial boot to setup might take a minute or two. But once the Windows installer loads into RAM, speed is fine.