Drive Letter Problem

I have a Lenovo desktop computer configured with a Windows 7 and Windows 8.1 in dual boot mode. Windows 7 was the as-delivered OS but now Windows 8.1 is the default.

Unlike any other computer where I have installed dual boot, this computer does not default to the C:/ drive as the "installed" drive for whatever OS is selected for boot. In otherwords, when Windows 7 is selected, the computer will boot up into Win 7 and File explorer (and Disk Manager) will show that WIndows 7 is running in the C: partition. But when Windows 8.1 is selected, or is allowed to boot by default, the computer will boot up into Windows 8.1 but File Explorer (and Disk Manager) will show that Windows 8.1 is running in the H: partition and the C: partition holds another OS, namely Windows 7.

I am interested in returning this computer to a single partition machine running Windows 8.1 and deleting Windows 7. But with the squirrelly arrangement of the drive designators, I am leary of deleting Windows 7 not knowing what the Master Boot Record will think of having no bootable OS in drive C: At this point, I am at a loss as to just what to do and I am looking for advice.

Thank you


Knows where his towel is.
Staff member
If you'd installed W8.1 "clean" from a booted DVD, it would have installed as "C".
Presumably you installed it to a new partition from a running W7, in which case W7 would be obliged to give it the first unused letter.
There's no rule that the OS has to be C, just a convention from the era of IBM twin-floppy PCs (1980's) where the HDD took the next available letter.
The only problems are 3rd-party related and becoming less prevalent. They resulted from sloppy programming which assumed that the OS would be C and hard-coded that assumption into various routines without checking the actual labelling.
There's no problem running Windows from any letter, whether or not a C disk exists.
You will probably not be able simply to remove W7 however, as it's odds-on that that's where your boot files reside.
You can use EasyBCD to copy the boot files onto the W8.1 partition