So if I understood you correctly you want future installations to go onto the new drive, right?
open regedit and navigate to
Locate the value named “ProgramFilesDir” in the right window, double click it and change the default value “C:\Program Files”
to your new directory path(address).
But whatever you do, make sure you read and understand this Article first: Microsoft does not support changing the location of the Program Files folder by modifying the ProgramFilesDir registry value
Mind you, I have 32 bit so your default folder might have a slightly different name
In the long run it might be safer to give the new path during installation (usually called Custom Install)