Question Macbook 7,1 (mid 2010) upgrade to 16GB RAM

[Adamistr0]

Hi, I have customer, who REALLY loves his old macbook and doesn't want anything else.
But he wants to upgrade this old beast to 16GB RAM. So I orderd 2x8 1600 MHz pack, that should be supported (and is specifically sold as Mac memory). But when I put it in, macbook only beeps once every 5 seconds - ram issue.
Only way to get it working is to place 1 old stick and 1 new stick, then memory works in 1066MHz mode.

Is there any way to set the frequency of RAM? I think the issue is that it can not work in 1600 MHz mode.

 

[lvt]

Let's be realist, that "beast" is at a stage called "end of life", if your customer is satisfied with how the laptop is currently running, why should you care about whether the RAM is 1066Mhz or 1600Mhz?