No 1866 option, 32GB installed 16GB usable and poor overclocking options

[H2SS]

The build is:
Motherboard : MSI A790-G46 North Bridge AMD 970 & South Bridge AMD SB950
CPU: AMD Phenom II X4 975, Black Edition (HDZ975FBGMBOX)
RAM: Kingston HyperX FURY 32GB (4x8GB) 1866MHz DDR3 CL10 DIMM - Black (HX318C10FBK2)
Video: GIGABYTE Radeon HD 7970 GV-R797OC-3GD 3GB 384-Bit GDDR5
PSU: Raidmax Blackstone 700W 80 Plus Bronze ATX12V/ EPS12V Power Supply RX-700AC
SSD: Samsung SSD 840 256GB (Boot drive)
HDD: WD Green 2TB WD20EZRX (storage)
Optical: LG Electronics 14x Internal BDXL Blu-Ray Burner Rewriter WH14NS40

32GB RAM at 1333Mhz - 16 GB RAM at 1600Mhz and other issues
Respectfully, please don't tell me how I don't need 32 GB. I've read plenty of opinions as to how much RAM a PC needs. The point is irrelevant.
AHCI and HPET are enabled.
Most, if not all, CPU Bios functions are set to auto with the exception of spread spectrum-disabled and CPU multiplayer-20.5.

The issues:
1. I am unable to set the RAM at 1866mhz. The 970A-G46 motherboard only gives the option of 1066, 1333 and 1600 in the bios which is version 2.8. It is supposed to run DDR3 800/1066/1333/1600/1866/2133*(OC). Any idea why I can't see 1866?

2. In Windows 10 Pro when I have the memory set at 1333 or lower in the bios, I am able to use the full 32 GB. When I set it at 1600 Windows 10 shows 32 GB Ram, 16 GB usable and sometimes 24 GB usable. The rest is system reserved. Why?

3. The CPU is overclocked at (20.5x/200) @ 4.1 GHZ. It doesn't change either issues whether OC'd or running at base speed. The memory bus does change if overclock the speed past 200 on the processor however the system does not boot properly and I always have to revert to 200mhz. The only way I am able to overclock the CPU is by changing the multiplayer. Any Idea why this is? If I am able to get the CPU's speed overclocked I believe I may be able to solve the RAM speed as explained in #2. Another note: I cannot get MSI OC Genie II to work in Windows properly. I tried all sorts of combinations with auto, manaul, enable and disable, which led me to accomplishing everything in the bios.

Thank you in advance for taking time to answer these.

 

[Darkbreeze]

Doesn't matter what your board supports in this case. The MC on the CPU only supports the following:

Support for unregistered DIMMs up to PC2 8500(DDR2-1066MHz) and PC3 10600 (DDR3-1333MHz)

according to the AMD product page. Often, that can be disregarded or worked around depending on the CPU model. Intel is bad about only listing support for the baseline SPD profile of 1600mhz even when much higher clocks are supported, but in some cases, especially with AMD, what's listed might be all that will be achieved.

 

[H2SS]

Doesn't matter what your board supports in this case. The MC on the CPU only supports the following:

Support for unregistered DIMMs up to PC2 8500(DDR2-1066MHz) and PC3 10600 (DDR3-1333MHz)

according to the AMD product page. Often, that can be disregarded or worked around depending on the CPU model. Intel is bad about only listing support for the baseline SPD profile of 1600mhz even when much higher clocks are supported, but in some cases, especially with AMD, what's listed might be all that will be achieved.

I had that in the back of my mind and completely forgot about that. I doubt swapping the CPU is worth the cost just to get the speeds where the RAM is capable of running steadily. I've tried so many different OCing profiles and not one will allow me to have the full 32GB at 1600 MHZ. Running at 1333 it is. Id rather utilize all my RAM than a slight difference in RAM speed.

 

[Darkbreeze]

Agreed, somewhat. However, it MIGHT be possible to get to work right on BOTH counts. Quite often you can get still surpass what the CPU supports "natively" by increasing the memory voltage. I'd try it first at 1600mhz to see if you can even achieve that before trying for 1866. Even though the performance difference isn't terrifically different, I hate not being able to utilize any standard portion of my hardware.

I'd try to set the speed to 1600mhz, with your CPU OC enabled, and try incrementally increasing the DRAM voltage in small steps to see if you can get it to recognize and use the full 32GB. In many cases this works, with a caveat. AMD chips don't like the use of four modules in a LOT of scenarios, especially when "overclocking" the RAM. First I'd probably try it with only two modules, to see if you can get it stable at 1600mhz, then 1866mhz, using slightly higher memory voltage. Only increase the voltage in small steps between tries. A single push of the + button, probably equals something like .05v increments, or something along those lines depending on board model.

If you can get two of them to 1600mhz with 16GB, see if you can get four of them there. It may require an additional voltage increase on the memory beyond what was required to get it there with two modules, in order to do so. Then if you can get all four there, take two back out and try to get two of them at 1866mhz, then four, using the same method. Of course, that's all assuming you're even willing to try that. If not, then you're probably not losing a major chunk of performance, but these AMD chips do seem to show some additional pep when overclocked a good amount and with the memory at 1866mhz.