Windows shows 8GB RAM installed but 4GB RAM is usable

Do you have a 64 bit version of Windows 10 installed?

Press Windows key + X
Click System
Look under Device Specifications.

Does it say 32 or 64 bit operating system?

If it says 32 bit, you will need to migrate to Windows 10 64 bit.

Switching to Windows 10 64 bit is free, you don't have to pay for it. As long as you have a qualifying Windows 7 or 8 or Windows 10 license, you are entitled to use it.
Switching requires that you perform a new installation, that means files, applications and settings will be deleted.

You will have to reinstall applications and native 64 bit drivers.

Backup before migrating: How to: Create a system image in Windows 10 (http://answers.microsoft.com/en-us/windows/wiki...)


Step 1: Download Windows 10 64 bit then create a bootable copy:
How to download official Windows 10 ISO files
http://answers.microsoft.com/en-us/windows/wiki...

Step 2: Boot from the 64 bit Windows 10 install media, then perform a custom or clean install:

How to: Perform a custom installation of Windows (http://answers.microsoft.com/en-us/insider/wiki...) - Choose this option if you want to recover files from Windows.old (http://answers.microsoft.com/en-us/windows/wiki...)

How to: Perform a clean install of Windows 10 (http://answers.microsoft.com/en-us/insider/wiki...) - Choose this option if you want to erase the drive, files and applications will be deleted.

If you have 64 bit Windows 10 which is able to use more than 3.4gb RAM, then type Resource Monitor in Start Search, open it, click on Memory Tab, post back a screenshot of the output: http://windows.microsoft.com/en-us/windows-10/o...

Hi,
This article explains everything if it is due to Windows:
https://support.microsoft.com/en-in/help/978610...
You might have to fiddle out some BIOS Settings in order to decrease dedicated video RAM.