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2:19 AM
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Q: Only 3.3GB of RAM is used from 4.0 GB installed, how to use full memory?

user158509In w10-64bit, (also in w7-32bit, w8-32bit in multiboot) only 3.3 GB of RAM is used from the 4.0 GB installed DDR2 RAM. Is there any tweak to use the full 4 GB RAM? CPU Intel premium E2180 Dual Core 2 GHz Motherboard ASUSTeK P5G-MX, Chipset - Intel i945G Memory 2x2GB DDR2, 3448 usable Graphics ...

Was closed as a duplicate, in spite of the linked thread addressing entirely 32 bit OS limitations. The question specifically included a 64 bit OS and the answers from the aforementioned thread are not relevant. I was in the midst of writing an answer when it was closed.
The actual answer is because of memory reservation not address space/32 bit register limitations.
The answer is further down but not the selected one, does that not matter?
 
You're right. Reopened the question
 

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