Read those images carefully, very very carefully.
It says
Installed System memory 8.00 GB
Total System Memory 8.00 GB
Available System memory 5.61 GB
This is an accurate and correct statement, it registered that you had 8GB installed, but 2.39 GB is currently in use by windows and other applications, available memory only refers to non active memory, something could be cache on it but not in use or it could be entirely free, but any memory that is in active use by any running application doesn't count as available.
Your system is fine, your ram is fine and functioning properly.
Edit: Typing a bit slower than normal tonight