Question Half of my ram is hardware reserved

[Shelby172]

So I have been reading threads about the very same issue that I am experiencing, so maybe with more information someone can come up with an answer.
System MSI 760GM-P34 AMD FX4300 2X4GB ram.
BIOS reports only 4GB of system ram
Windows 10 pro 64 shows 4GB hardware reserved 4GB available.
This MB was equipped with onboard video which was disabled by using a discreet video card. All setting changes had no effect assumed it was a MB issue.
MB swap to a Gigabyte 970a with no onboard video same CPU but increased ram to 24GB.
Again UEFI reports 12GB system memory
Again Windows 10 reports 12GB hardware reserved, 12GB available.
At this point it was suggested that the CPU May have a bad memory controller.
MB swap number 3
ASUS 970a pro gaming aura
AMD FX4350 (new CPU)
Dual nVidia GTX 550 Ti in SLI configuration.

Same problem UEFI reports 12GB system memory.
Windows 10 reports 12GB hardware reserved 12GB usable.

System number 2
ASRock 970a-3.1/G AMD FX8350
32GB 4X8GB DDR3 12800(1600)
1TB m.2 SSD
UEFI reports 32GB system memory
Windows 10pro 64 reports 32GB with 25MB hardware reserved.

System number 3
Supermicro H8DGi-F dual AMD Opteron 6376
32 GB 8X4GB DDR3 12800E (ECC)
Dual 2TB Seagate HDD’s
nVidia GTX 780
BIOS reports 32GB system memory
Windows 10pro 64 reports 32GB ram with 2MB hardware reserved.

I have built 6 systems 4 AMD 2 Intel based and only one has the half total ram hardware reserved issue. I have seen others have the same issue with AMD 6xxx series CPU’s so I don’t believe it is the AMD 4xxx series CPU. The HDD was originally used in my old VISTA 32bit machine with Windows 10pro 64 installed. What gives? Anyone have any ideas?

 

[Calvin7]

Memory may be incompatible in the combinations you make. With no part numbers of memory, memory is not identified.

 

[Shelby172]

I had thought of this too. The MSI board only had two memory slots. Originally equipped with the 2X4GB DIMMS. Same issue exhibited. Upgrade ram to 2X8GB same issue. The other two boards have four slots and still exhibit the same issue. I also have a DELL 7010 with an Intel Core i7 3770 with 2X4GB and 2X2GB for a total of 12GB and it does not have this problem. At this point the only common denominator is the HDD. I have had it for 15 years as it originally had Windows Vista 32. I have read that BIOS viruses are rare but I am running out of ideas since there is no consistency between the systems.