[SOLVED] HDD still full even after i clean it!

[using google in BSOD]

my HDD space left on the C: drive is 95 GB left. wait, it maybe looks a lot but for my pc, no.
my performance decreased if the space left in the C: drive is lower than 100.
i've tried disk cleanup, cleaning the temp and %temp% files , defragment (i know it doesn't increase space but at least it can run better. but nothing happened), and CCleaner.
there is avast antivirus in my PC. and it detects no virus.
maybe there is a way to stop my PC from downloading files to the C: drive although i've changed my main downloading location to the second partition or an external HDD.
thank you for helping!

 

[USAFRet]

Install and run either WinDirStat, or WizTree.

Run as Administrator, selecting only the drive in question.
Post a screencap here.

Also, a screencap of your Disk Management window.

 

[using google in BSOD]

which one is better?

 

[USAFRet]

which one is better?

Yes. Either.

 

[using google in BSOD]

ok thanks