Windows 10: 12gb ram but only 2.96gb is usable

Hello so I bought a 8gb ram for my PC windows 10 but the problem it says 2.96 gb usable of my 12gb ram I tried reinstalling windows 10 64bit but it doesn't work also when I try to open the memtest which is on the USB bootable it says cannot run on windows 32bit mode even though my CPU is 64bit.

:)

 

12GB RAM installed but only usable 3.45GB Windows 10 64bit

I had this issue,

64 bit windows 10 pro 12 gb ram in triple channel so 3x4gb it said 12gb ram (4gb usable) checked settings in msconfig updated bios took RAM out cleared CMOS put RAM back in and it worked.

 

12GB RAM installed but only usable 3.45GB Windows 10 64bit

Hi, I just upgraded my laptop (Asus X550ZE) from 4GB to 12GB, somehow I notice my windows detected 12GB (3.45GB usable) only just like the screenshot, may I know what is going on? How can I optimize to use all the RAM? My windows is Windows 10 with 64bit
Home Single Language.

 

Ram 32GB (31.9 usable)

below are reported fixes

• update BIOS
• Take out RAM sticks completely re-sit (this worked for me weird)
• Run>Ms-config>Boot options>advanced boot>un-tick maximum memory

I had windows 7 Pro 64bit upgraded to windows 10 pro 64 bit I had 12gb 3x4 gb it sais 12gb (usable 4gb)

Turning of computer completely unplugging cable from power supple making sure no power is left in the motherboard or power supply, removed all the RAM reinserted this fixed the problem which is weird considering before upgrade windows 7 pro saw all 12 gb
and could use it.