1. According to my personal experience, I use Rubik's Cube or Win7 optimizer, which can effectively delete useless system files and junk files installed in C partition.

Second, however, the ability to clean up the C partition with third-party software is limited, so the following methods can be considered:

1. Move files outside the system to other partitions; Uninstall the application software and games installed in partition C and reinstall them in other partitions.

2. Turn off system restore. Right-click the computer on the desktop-Properties-Advanced System Settings-System Protection-Configuration-click "Turn off System Protection"-OK.

3. Disable the hibernation function. Open the "Run" window, enter the "cmd" command and press enter, open the command prompt window, enter "powercfg -h off" and press enter.

4. Move the virtual memory to another partition. Right-click the desktop computer-Properties-Advanced System Settings-Advanced-Settings-Advanced-Change-click on drive C-select "No Paged File (n)"-"Settings", and the virtual memory in drive C will disappear; Then select drive D, select "Custom Size"-enter values in the following two text boxes of "Initial Size" and "Maximum Value"-Set-OK-restart.