Why is Linux using so much RAM when no applications are open?

For comparison, an idle desktop with roughly 32 GiB of RAM often uses only a few GiB for ordinary processes, although cache can make the used number look larger. If a process monitor shows no normal application using the missing memory, investigate kernel memory, graphics drivers, containers, or a possible memory leak. Increasing swap or configuring compressed swap such as zram can help with pressure, but it is not a substitute for finding a runaway process.

The `free` output is concerning mainly because the swap area is only about 512 MiB and is already almost full. Increase the swap size, then check whether the system is actively swapping. A larger swap area will not identify the original memory consumer, but it can reduce crashes and severe stuttering when RAM pressure occurs.

Use a process monitor such as `top`, `htop`, or `btop`, and sort by memory usage. The task manager may not be showing every process clearly. These tools should reveal which applications or services are consuming the RAM.

Remember that the `used` column includes memory used by the kernel and caches, so it is not always the amount that applications cannot reclaim. The more useful number here is `available`, which is only about 9 GiB. Check the top memory-consuming processes with `htop` or `btop`, and compare their total usage with the output from `free -h`.