Not all RAM available in OS?

Question

I have 24GB of installed memory, 8GB 1600Mhz and 16GB 2133Mhz. However usable memory is at 6.96GB??

1. I have followed msconfig -> boot -> advanced options and have un-ticked "maximum memory" but i didn't help.
2. I have also tried leaving 16GB sticks but usable memory is still at 6.96GB.

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Further information about the system: I am running AMD FX-8320 on "MSI 970 GAMING Socket AM3+ 7.1-Channel HD Audio ATX Motherboard". RAM:

• Corsair Vengeance 16gb (2 X 8gb) Memory Kit Pc3-17066 2133mhz Ddr3 Dimm
• Samsung 2 x 4gb 1Rx8 PC3-12800U-11-13-A1 1600Mhz

BIOS does show a full amount of RAM.

I have installed new RAM today (16GB), hence the question.

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I am running windows 10 64-bit operating system, x64-based processor.

Answer 1

The 8 GB <-> 6.9 GB discrepancy is normal due to memory taken from the system RAM for use by the on-board GPU.

Seems that your Bios sees the RAM but doesn't actually tell the OS there is more than 8 GB installed.

It is not clear from your question whether you already tried this: Installing the 8GB RAM's in place of the original 4GB RAM's ? In some cases the BIOS likes it better if the faster RAM is in the 1st slots and the slower RAM in the 2nd set. Other BIOS like them the other way around.

Try to do a factory reset of the BIOS settings. (Write down the original settings so you can reconfigure any specifics later...)

If that didn't help: You most likely need to update the BIOS (if possible) to get this to work.
Or you need other RAM. It could be that you laptop just doesn't like this particular set of RAM's.

Answer 2

I have solved the problem by specifying amount of RAM in the "msconfig -> boot -> advanced options". After which i was able to achieve 15GB of usable RAM.

But, I was unable to use my 2x4GB sticks with 2x8GB sticks; for some odd reason GPU wouldn't start due to which i couldn't use computer.