Of the 16GB of RAM, the OS sees only 8GB, what's the problem?

Question

Iron

What has been done:
Bios updated first to 2203 fresh.
Memtest86+ with each bar separately, in different slots, sees the bars, tests without errors. If Paste all 4 or 3 sees only 8GB. Same with any other OS: DOS, CentOS, HBCD2018 (W10).
In HBCD2018, the picture is as follows:

spoiler

msconfig check the box for all memory ceiling 8192,
mdsched passed without errors.
What is interesting in the BIOS, when you boot from any OS, you can see that no one has fallen off all the bars in place, then we boot from any OS without rebooting and get 8GB.
Hardware:
Motherboard Asus b85-pro gamer
CPU intel i5-4570 3.2ghz
DRAM Kingstone 4096MB 1600MHz x4 pcs
Video MSI GTX 1060 6GB

Answer 1

Once tagged, you will have to answer :)
Your problem may have several reasons:
1. Failure of one of the channels of the RAM controller
2. Damage to the socket legs (or blade)
3. Damage to the contacts in the RAM connector
4. Not working RAM
5. Incompatible RAM
B BIOS, you see all all the bars as installed, because the check for the presence of RAM in the connector goes by reading the SPD, not only that the RAM is working (depending on the BIOS, the behavior may change), the final initialization is already at boot.
To diagnose a processor and half of the points, for a good percentage, insert it into a known working mother with a known working RAM, if the entire volume is determined, then we consider the percent alive, insert our RAM into the mother and also look, everything has been determined, which means it is alive and does not conflict with each other.
We assume mechanical damage to our mother and repair it.
If another mother has the same problem, then we assume that either a percent or an oz is a corpse / conflict - depending on the stage.
PS NOT!!! to insert other processors, RAM into your mother, there is a chance to ruin someone else's percent / RAM and the chances are great!

Answer 2

look in the BIOS to see if it's there

Answer 3

earlier on older systems there was a problem of limited memory for Windows and the bit depth of the system. It's like an option, what bit depth? Also, maybe you downloaded the build, and there is an injector in the system, which physically limits it, preventing you from seeing the real costs of memory and computing power, clogging them with some kind of your own process