Suppose you want the following partitions:
c: (200 GB), D: (reserved for recovery, so not touching this), e: (250 GB) and F: (230 GB), follow these steps:
1. right click on "Computer" on desktop and select 'manage'.
2. Select 'Disk Management' form the left pane.
3. After disk management opens, right click on C: drive appearing in middle and select 'Shrink Volume'.
4. In 'Enter the amount of space to shrink in MB', enter the space to shrink (this many MBs will be reduced from you existing C: drive). As we are creating two new partitions of 250 + 230 = 480 GB, enter 280x1024 = 491520 MB and continue. Wait for the porcess to complete.
5. Now, there will be a space shown right to C: drive indicated as 'Unallocated space". Right click on it and select 'New simple volume'. Enter the size of first partition in MB, i.e., 250 x 1024 = 256000 MB and select NTFS as file system and continue. Wait for the process to continue.6. Similarly, right click on remaining Unallocated Space and create a new partition of desired size.
6. Thats it!
you are partitioning c drive then i think you will have to format/reinstall everything windows and softwares drivers etc.
i don't know if you can partition without formatting never done so no idea.
it will be advisable to give more space to c drive and do not change default path to install softwares/games in some cases if you want.
If C: drive is shrunk to create new partitions, then there is absolutely no need to re-format the drive.
Note: if shrinking was unsuccessful, defragment the c drive before shrinking.