How do I keep my processor memory balance?

Dear TechyV Experts, I would like to ask what might be the problem of my computer. Because every time I play online games and PC games, my memory drops to a thousand bytes. I am sure that my computer has still 10GB of free memory in each disks. I hope you can suggest options on how to avoid this sudden fluctuation in my computer memory. I would be waiting for your valued answers. Thank you and have a good day!
