So I built my own PC earlier this year, after having to put my project on hold for about a year. After getting it operational, and sorting through minor technical difficulties, this last one remains: my PC will only use 3.9 of the 16 GB of RAM I installed.

When I check my system information, I've verified that it recognizes my "installed physical memory" of 16.0 GB, but that my "total physical memory" is 3.9 GB.

I'm currently using an Asus M5A97 LE R2.0 motherboard (which is capable of handling up to 32 GB of RAM) and Windows 10 Home 64-bit edition and a 64-bit CPU. I've turned off RAM limiting through the msconfig menu, and inspecting the RAM sticks themselves hasn't shown any apparent damage to the sticks. I'm using 2 4 GB sticks and 1 8 GB stick.

Could someone help me in figuring out how to get my PC to use the other 12 GB of RAM?