Installing SQL Server on not the default path I am trying to install SQL Server 2012 on a machine which has


764 Mb Free Space on C:
832520 Mb Free Space on D:


So during the installation process I changed the default location from C:\Program Files\Microsoft SQL Server\ to D:\Microsoft SQL Server\

But during the Disk Space Requirements check I cannot proceed saying I dont have enough space left on C:



Is it possible to not use C: at all or is it not configurable?
From BOL:

During installation of SQL Server 2012, Windows Installer creates temporary files on the system drive. Before you run Setup to install or upgrade SQL Server, verify that you have at least 6.0 GB of available disk space on the system drive for these files. This requirement applies even if you install SQL Server components to a non-default drive.

http://msdn.microsoft.com/en-us/library/ms143506(v=sql.110).aspx

You still need 6GB free on the system drive, regardless of where you are installing it.  Although, depending on your options for install, that may be smaller, as in your case.