Read about mixing computer memory.
Identify your motherboard with powershell. See if your choice of motherboard and cpu supports 16GB of the type of memory you have installed by reading your manual.
Get-WmiObject -Class Win32_BaseBoard | Format-Table Manufacturer, Product, SerialNumber, Version
Identify your memory with powershell:
Get-WmiObject win32_physicalmemory | Format-Table Manufacturer,Banklabel,Configuredclockspeed,Devicelocator,Capacity,Serialnumber -autosize
If you have used a supported amount / type of memory read the following.
Windows 10 Won’t Use Full RAM
- Modify RAM used on Boot
- BIOS limit Windows from using the full amount of RAM installed
- Windows 10 showed less amount of RAM usable due to a physical defect