If it was using 100% that's a good thing. That would not be a failure.
So let's hear more about what's running on this PC and what you do to avoid malware.
I have a fairly recently built pc and have noticed since around the beginning that my memory is almost always at 85% or higher. I don't understand why this issue is happening. I have closed all applications and just sat at the desktop and it still gives reading like 90%. I am currently running 8gb of ram so I see no need for it to be failing like this.

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