Why is nearly all 16 GB of my RAM used when no programs are open?

Start by checking exactly what is consuming the memory instead of relying only on the overall percentage. Disable unnecessary startup apps, close or restart any program that keeps growing in memory usage, and run a full security scan. If no normal application accounts for it, a memory leak from a driver or background service is possible.

Windows does use spare memory for caching and preloading, so a high percentage by itself isn’t necessarily a problem. However, nearly all 16 GB being committed while idle, especially with game stuttering, is worth investigating. Open Task Manager, sort the Processes tab by Memory, and also check the Performance tab for the difference between In use, Cached, Committed, and Available memory.

Update Windows, your motherboard chipset and networking drivers, and the NVIDIA graphics driver. Faulty or outdated drivers can sometimes cause unusually high memory usage. If the problem began recently, checking Reliability Monitor or temporarily rolling back the most recent driver may help identify the cause.

If Task Manager shows very little memory assigned to applications but the total is still almost full, check the Performance tab’s memory details and Resource Monitor. A large non-paged pool or unusually high hardware-reserved memory can point to a driver or hardware configuration issue. Also make sure your virtual memory/page file is set to be managed automatically.