Why Empty RAM is Useless
However, this isn’t a concern at all. Whether your RAM is full of cached files or completely empty, it’s all available for programs that really need it. Cached data in your RAM is marked as low-priority, and it’s instantly discarded as soon as the memory is needed for something else.
Because this data can be instantly discarded when necessary, there’s no disadvantage to using the RAM for cache. (The one potential disadvantage is users who don’t understand what’s going on becoming confused.)
Empty RAM is useless. It’s not any faster for the computer to write data to empty RAM, nor does empty RAM use less power. In fact, assuming you’re launching a program that may already be present in your RAM’s file cache, programs will load much faster when your RAM is used rather than when it’s empty.