Remember you wrote you have a CARD (6900) so I can't guess this is some laptop that the graphics uses (shares?) main RAM.
A Web Speccy report could reveal what's up. Here's how: https://www.piriform.com/docs/speccy/using-speccy/publishing-a-speccy-profile-to-the-web
When you get into this area, make, model, PC type information helps.
My computer has two 4GB sticks of ram installed. 4GB is usable, but the other 4GB is hardware reserved. I want to use all 8GB obviously, but how do I free up this extra RAM? Ive tried clicking maximum memory under msconfig and Ive tried re-installing windows 10. My videocard is an AMD Radeon HD 6900 Series. Is this a card that has dedicated memory? Would that explain the 4gb loss?
Thanks

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