I wanted to shrink my C: partition, make a new partition in the unallocated space and install windows 10 on it. Since people are used to having C: as the main drive letter, some programs could be hard coded to use that and overwrite some files in my windows 7 partition. What are the chances of that happening? Is it safe enough to be doing this?

Extra information: currently using Windows 7 Ultimate 64 Bit Edition

1 Answer 1


When booting up a second or third Windows from a different partition their own system partition will usually have drive letter C: as well.

The C: from your other Windows will just have a different drive letter.

In that respect it is pretty safe to run dual-boot multiple Windows on the same machine.

On problem I can think of is the boot sector / boot files. If you install a newer OS first and than an older one, it may overwrite the newer boot files and the newer OS wont be unable to boot. This is very obvious with Windows XP and anything newer, but a Windows 8 or 10 may also not boot from the Windows 7 boot files. So make sure to install the newer OS last.

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