32 GB of ram, only 16 is read by bios, windows and ubuntu

[s903s]

Hi everyone, I have an issue since some years that I have never succeeded to understand on what it depends I have a computer assembled by me with these features:
Processor: Intel i73770
Motherboard: asus P8z77-v deluxe
Ram: 32 GB, corsair CMz32GX3M4X1866C10
GPU: Gainward geforce 680
When I have assembled this pc for some months both windows and ubuntu they was reading 32 GB of ram fully. After some months suddenly it reads 16 GB of ram, from bios also if the rams are 1866 mhz I can take them only maximum to 1600 mhz. I can't understand why I have this issue and how to solve it. I attach to this conversation some screen of cpuz and windows properties.
Thank you for helping

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[PP Mguire]

Clear your bios and if that doesn't work try each stick individually. Currently your RAM is only running at 1333. For 1866 you need to use XMP profile.

 

[MidnightShadow]

I would try to reseat each chip of RAM first as that would be the quickest and easiest. I've seen RAM do some strange things, and reseating it usually resolves those issues. RAM can be a fickle thing.

 

[PP Mguire]

I would try to reseat each chip of RAM first as that would be the quickest and easiest. I've seen RAM do some strange things, and reseating it usually resolves those issues. RAM can be a fickle thing.

Asus boards have a habit of disabling sticks of RAM if unstable that's why I told him reset the bios first. It's more than likely why his speed is set to 1333 which is default for IB platform.

 

[Crenewer]

I would try to reseat each chip of RAM first as that would be the quickest and easiest. I've seen RAM do some strange things, and reseating it usually resolves those issues. RAM can be a fickle thing.

Agreed. This issue happened to me once. My laptop has 8 GB of RAM installed, but for some reason it only read 4 GB, and reseating the RAM fixed it.