I had a friend bring me his HP Laptop to be clean installed. It wouldn't boot. Had corrupted files and wouldn't boot. I do not know if his BIOS was from Win 7 ERA or UEFI era. Here is what I tried and my results. My question is why did the one scenario not work? I started with my UEFI prepared boot USB drive and it is formatted Fat32. His computer boot menu did not recognize it. So I moved on to my next boot USB that I prepared from a neat program I got on here or nsane site where it will boot either Legacy or UEFI. It has 2 partitions the 1st is Fat32 with boot files and the 2nd is NTFS formatted with the install files. That drive worked. I also tried my Sergi Strelec Win PE boot USB that is formatted Fat 32 and it worked. So my question is....If my UEFI boot USB didn't work..why did the Strelec USB boot as they are both Fat32 which is needed for a UEFI boot. If you have a legacy BIOS..eg: Win 7..What format does the USB need to be then? The Win 10 has to be Fat32. Straighten me out on this matter please.