Gigabyte Motherboard Windows 7 Ultimate x64 7.97 GB usable

[WinSevinStable]

Hi everyone I know making a new thread is annoying but I've compiled all the data about my PC Build so a pro genius Windows 7 User can Diagnose this.
So as it says in the title my PC is installed with 24GB but only 7.97GB is usable I've tried a bunch of things with MSconfig and settings but I can't figure out a fix.

 

[flavallee]

Assuming your "My System Specs" is still up to date, it says the Gigabyte GA-970A-DS3P motherboard in your computer has 8 GB of DDR3 RAM.

According to the motherboard's support site, it has 4 DIMM slots and supports up to 64 GB (16 GB X 4) of DDR3 RAM.

If it now has 24 GB of RAM, how many modules are installed, and what are their capacities and speed?

 

[WinSevinStable]

There are 2 sticks of 8 GB Kingston PC3-12800 (800MHz)
and 1 stick of 8 GB PNY PC3-12800H (800MHz)

 

[flavallee]

You didn't provide the exact model numbers of those Kingston and PNY modules, so we don't know what their specs (voltage, latency, etc.) are.

You also didn't say what setting changes you made in System Configuration Utility(msconfig) and elsewhere.

Note: "Number of processors" and "Maximum memory" should both be unchecked and greyed out.