The RAM can be incompatible yet apps can read the SPD chip on the sticks. Just because the SPD (see https://en.wikipedia.org/wiki/Serial_presence_detect ) does not indicate the stick is compatible. It only means the stick fit in the socket and nothing more.
It can also mean there is a defective RAM socket. There's not much mystery here.
What I would try if you believe the memory is compatible is to be sure the BIOS is current since the BIOS is often updated to add more memory stick compatibility.
In closing, this is why I often go to Crucial.com.
I just purchase (2x 8GB DDR3 1866MHz PC3-14900R). I was trying to upgrade my current (1x 4GB DDR3 PC3-10700)<I couldn't find the MHz for it. So... when i received the new rams i immediately swapped it. Then i started hearing beeping sounds, i took one new rams out and place the old ram next to the new one (2nd Slot) Here : https://imgur.com/84bHT7E (I basically bonded the new ram with the old ram)
After doing that it worked, but the thing is..... CPUZ showed up with 12GB (Here: https://imgur.com/AYPv6C5) memory size but System Information showed up with 4 GB (Here: https://imgur.com/VYUCdXQ)
Here is Slot #1(New One) : https://imgur.com/aIRNaYX
Here is the old Ram Slot#2: https://imgur.com/DUb487Q
My main board: https://imgur.com/Q0yYFOU
My CPU : https://imgur.com/mREKw0Z
Here is the link for my PC`s components: https://support.hp.com/us-en/document/c03141285.
So my question is what is happening.....?
I also heard of increasing the Voltage for the new ram ik it is set to 1.50V but my bios does not have the options to do it.
Can someone please help me out?

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