Installed 16gb of RAM but Bios and Windows 10 only recognizes 8gb

[Moonpreacher]

So, I had a MSI FM2A75MA-E35 FM2+ motherboard with 1x8gb DDR3 ram.

Installed a new 8gb DDR3 to upgrade to 16gb and nothing.

When turned on, the BIOS only detects 8gb. Not good!

So tried switching the modules and tested them, no problem at all but still only 8gb in BIOS.

But in Windows 10 it says I have 16gb but only 7.95gb are usable.

And CPU-Z does show the 16Gb but in single mode.

So I installed ClickBiosII provided in the motherboard drivers, it works as a BIOS shell
for Windows...and the 16gb are shown!

If the BIOS didn´t detect the extra RAM then in no way (in theory) should Windows detect it. But if Windows 10 detect it, why can´t I use it in total?

 

[Moonpreacher]

No solution but selling the old 8gb module and buy another equal to the new one

 

[alsmith]

Are both memory modules the same make, speed etc? Is there a bios setting for the memory mode- single channel /dual channel? Have you got the latest bios?