MacBook randomly crashes after RAM swap | Mac

Recently I decided to give an older MacBook Pro (Mid 2010, 13 inch) a little RAM upgrade. After changing from the original 4GB (2 x 2GB @1067MHz) to 16GB (2x 8GB @1600MHz Corsair “Mac Memory”) the Macbook didn’t boot up.So I began playing around a bit.I then found out that the MacBook itself wasn’t able to run the 1600MHz sticks at the right speed of 1067MHz which is the highest possible since it only got a 1067MHz front bus. I then replaced only one of the original RAM sticks with a new one (2GB 1067MHz+8GB 1600MHz) and the MacBook started and seemed to run normally. Even though dual channel wasn’t possible I was glad to at least have a bit more memory on it. But since then the MacBook randomly crashes in variable scenarios. One time while watching Netflix, another time while writing a document, light tasks only and it just crashes – screen freezes, flickers, lines on it then shuts down.I’m unsure whats the actual problem it got. Still thinking about the difference in memory speed. So I got two questions:

• Is it somehow possible to choose a different ram speed to permanently decrease the speed of the new RAM kit down to 1067MHz?
• Are there known issues when running single channel instead of dual channel?
• Does anyone here got similar problems?

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These are the original specs (in German, I guess meanings are clear tho)

I also replaced the original hdd with a faster ssd which didn’t gave me any issues at all.btw: This is the Core 2 Duo model so there are no kernel panics or anything if I put in more than 8GB of RAM.

I’d really appreciate your help! – Thanks in advance!