Mismatched RAM?

So I bought a very cheap used 4GB DDR4-3200 stick for the mainboard as router/server/etc project. Then someone just gave me an 8GB DDR4-2666 module.

Can I mix the two sizes in slot 0 and slot 1? I assume it will run the 4GB at 2666 instead to match the 8GB? Or are the different speeds in the different slots going to be a no go?

Thanks all

This is the support page for RAM: https://knowledgebase.frame.work/what-memory-dram-parts-are-compatible-with-the-framework-laptop-ry_jbS8Ru

There are several posts on RAM here on the community and it looks like mixing is possible with some sticks but performance will likely be affected and some combinations may cause the system to fail to boot. Search for RAM and take a look at some of the conversations.

If you install one single 16GB DDR4-3200MHz module in your system, it will only run at 1600MHz, known as (single-data rate). Also, if you install two or more RAM modules, such as one 16GB DDR4-3200 and one 8GB DDR4-3200, the dual-channel mode will be disabled, which can seriously reduce your PC’s performance.

Sounds like trial and error is the only way to know for sure. I think I’ll just stick with the 8GB single module only.

Thanks for the replies.