ram speed

Hi, I have a Razer Blade 15 (2018). This laptop comes standard with 16Gb DDR4 SODIMM 2667Mhz RAM (2x 8Gb). As it can be extended to 64Gb I’d like to do this within the next few weeks. My question is, I’d like to go for RAM that is 3200Mhz rather than 2667Mhz for obvious reasons, how do I know...

I have an unused Gigabyte motherboard that will accept up to 16GB of DDR3 RAM running at up to 2200 MHz. If I install 2 x 8GB of 1600 MHz RAM will it cause any problems? I ask because 2200 MHz Ram seems to be unavailable; 2 x 8GB of DDR3 PC3-12800 (1600 MHz) RAM only costs about £2 more than 2...