Windows 10: Windows reserves 1 full stick of ram for no good reason

I hope anyone can help, I have seen posts relating to this before but mines slightly different.If I slot in 1x 8gb stick of ram everything is fine, however I need 16gb to run some of my more powerful apps and games. As soon as I slot in my second identical stick of 8gb ram windows reserves the full second stick...I have tried 2 different sets of Ram both 8gb different brand gaming ram and still persists so it's definitely not a stick issue. I have also tried Different slot configuration still no luck. I have tried updating bios no luck.Did a brand new windows install no luck... Did all the bio

:)

 

Installing windows off of a USB stick

Step By Step from vista:
From admin cmd prompt

1. diskpart
1a. list disk
2. select disk 1 (replace 1 with your usb drive)
3. clean
4. create partition primary
5. select partition 1 (replace 1 with your usb drive)
6. active
7. format fs=fat32
8. assign
9. exit

Copy Windows Vista's DVD ROM content to the Flash Drive

xcopy d:\*.* /s/e/f e:\ (d being your vista cd and e being your usb stick)

And that's it, boot off your usb disk

 

Hardware Reserved 4GB (DIMM Slot 1B)

So recently my task manager started showing that only 12GB of my 16GB DDR3 RAM in Dual Channel was available stating "Hardware Reserved 4.0 GB"

These are the steps I've currently taken to attempt to rectify the issue.

1. Flashed BIOS
   
2. Wiped OS and installed to a new drive
   
3. Set max page file size to recommended (2.5GB)
   
4. Maximum memory isn't enabled in advanced boot options
   
5. Replaced the odd stick of RAM (I had a Kingston HyperX Fury) with the same model (now all Corsair Vengeance) so now all sticks match
   
6. Resetting CMOS fixed it for a few hours before returning.
   

I want to avoid the idea that the DIMM slot is faulty due to a CMOS reset fixing it (even if temporarily).

The RAM I'm using is: CMZ12GX3M3A1600C9 (3) and CMZ4GX3M1A1600C9 (1) Both the same model of RAM, but the 3 came in a kit for 12GB whilst the other came as a single kit of 4GB, hence the slight difference in the part numbers.

The motherboard I'm using is 990FXA-UD3 R5.

I'm asking as a seperate question due to the fact I've tried every other suggestion in the other questions and now feel that my situation is unique enough for it's own question.

 

Half of RAM 'Hardware Reserved'

I have 32GB of RAM installed and half is "hardware reserved" by Windows. I've tried every suggestion I can find, including moving the modules around to different slots. My MB does not have onboard graphics.

Specs:

• Motherboard: Gigabyte GA-AX370M-DS3H (BIOS on latest firmware)
• CPU: Ryzen 7 2700X (upgraded from 1700x and it didn't help)
• RAM: Corsair VENGEANCE® LPX 32GB (2 x 16GB) DDR4 DRAM 2400MHz C16 Memory Kit
• GPU: Nvidia RTX-2060 Super

The BIOS, Windows, CPUZ and HWInfo all show 32GB installed and both slots used, but Windows says "Hardware Reserved: 16.1GB".

This was occurring on Windows 10. I am currently running Windows 11 (beta channel) and it didn't help. I also upgraded my CPU from a Ryzen 7 1700 with no change.

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