# Windows – How to switch drive letters efficiently

hard drivewindows 7

I have 2 storage drives, one is a hard drive and the other is an SSD.

I used to run windows on the hard drive, and left the SSD untouched. but then I installed another windows copy on the SSD (which has the E:/ letter).

The drives currently are:

C:/ [Hard Drive] Has old OS

E:/ [SSD] Has new OS

I'd like to make the new OS (SSD) as the primary drive, therefore having the C:/ letter instead.

I tried switching the old C:/ to H:/ and then switch E:/ to C:/ but it said: Invalid parameter.

Anyone has an idea how to do this?

P.S. I really don't want to reinstall E:/ again if possible.