I just purchased the (11th Gen Intel® Core™) - i7-1165G7 mainboard for a little project I am working on. However, I am curious if the DDR4 2133 RAM I have laying around (16Gb sticks by Axiom, still sealed in anti-static bags) would work. I know it will be a little slower if it does, but it would save me some up front cash if it does.
Chances are good that it WILL work, Maybe someone on here has had a similar experience and can confirm 
. If you were near me I would happily sell you the 16GB DDR4 3200 RAM that I have laying around $40CAD lol. It was the first memory I had in my i7-1165G7 until I decided I wanted more 
No harm in trying, should work, DDR4 is a pretty tried and tested platform by now!