It may just work. See here for reasons: http://www.apachefriends.org/en/xampp-windows.html#521
(it should work at root directory of any drive, and need to run setup_xampp.bat in xampp package if want to place it in a non-root directory)
OpenEMR can be installed on auxillary drives, but will it run slower than on C-drive? Is speed not a concern if the microprocessors and the RAM’s are powerful enough?
If we are talking windows, you can just move the xampp directory to any drive you want. From that directory you have to run xampp control to turn on apache and mysql. I made an encrypted drive called M: using truecrypt and I run xampp from there so if somebody stole my server it is encrypted at rest. It is a bit slow, but can actually be run from a thumb drive if you want and those can be encrypted as well. You just have to use windows explorer to find and run xampp control from where you have placed it on your computer. You also can’t run it as a service unless it is on the C: drive, so if you reboot you have to restart it manually.