msi gl63 8re ram compatibility

Choose the 16GB 2666MHz stick. Mixing two speeds will lower both to the lowest speed of the two. Also regarding warranty, you can install the memory without issues, as long as you do not tamper with other parts of the laptop. The RAM upgrade is allowed by users to do and voids warranty only in exceptional cases by the system manufacturers.

If you are good with installing memory on laptops, then I would suggest you to do it, or you can buy the RAM that you want, go to MSI service center in your locality and request them to install the memory you purchased. The former is the better choice if you are experienced with 2018 laptop models that have made the rear panel a little difficult than previous years models.