Windows' RAM Limit

I have Windows 7 Home Premium (64-bit) installed on my computer and the motherboard is able to handle up to 32 GB of RAM. I recently upgraded my computer to 20 GB of RAM, but the operating system says that only 16 GB of the 20 GB I installed is usable.

I have four slots on the motherboard. I installed two 8 GB sticks of RAM closest to the CPU and two 2 GB sticks of RAM in the remaining slots. I made sure that the RAM sticks are the same (DDR3, 1600 MHz). Just in case it matters, I also installed a GTX 770 GPU with 2 GB of memory. Here is a list of the specifications for my motherboard: P8P67_LE Motherboard (Asus).

What am I doing wrong? Why am I seeing this issue in my computer’s Control Panel?

Windows 7 Home Premium supports up to 16 GB of RAM. That is why only part of what you have installed is showing as usable even though your computer supports the extra RAM and does detect it. It is a licensing issue in Windows 7 that only allows it to use 16 GB of RAM. You can view the memory limits for various versions of Windows and Windows Server releases via the link below:

Physical Memory Limits for Windows and Windows Server Releases Note: This link is set to the Windows 7 portion of the support page.