I was surprised to open Task Manager on my PC, as the RAM it was showing was 8GB, because actual RAM I installed was 16GB. I instantly opened up my cabinet and put both my 8GB RAMs into different slots. Rebooted and opened up dxdiag
to confirm I had 16GB RAM.
But Task Manager still showed 8GB RAM.
On the other hand, the UEFI says I have only 8GB RAM available. Here are my motherboard details:
Manufacturer Product SerialNumber Version
ASUSTeK COMPUTER INC. M5A97 R2.0 141134705803134 Rev 1.xx
I've read this post: RAM usage % on Task Manager lower than actual RAM but I don't find anything relevant. Earlier, Task Manager used to show full 16GB RAM inside the left column.
Best Answer
I noticed there is a lot of hardware reserved RAM (a bit more than 8GB).
According to some quick research, there is incompatibility between your motherboard and some of the DIMMs.
According to the answer from this superuser question:
Also, according to an answer from Tom's Hardware forum (slightly modified):
Another similar problem solved: