Hi Firat,
My name is Igor, it's a pleasure for me to help others and I'll do all my best to help you.
In fact, you have some programs running, you may look at processes list in Task manager or use tasklist command in the command prompt.
4-5 GB is normal now due to high memory usage by Internet-related programs and browsers.
Please note, memory usage at Processes tabs shows only one way of memory using - private memory set - and does not take into account any other method.
Detailed memory usage analysis may be done with RAMMap tool. You may show the first tab of the program for a clarification. https://learn.microsoft.com/en-us/sysinternals/...