Should I replace my old 2x8GB RAM kit with a new 2x16GB kit instead of mixing sticks?

Yes, replace the old 2x8GB with a fresh 2x16GB 3600MHz CL16 kit. Mixing two separate kits is a gamble on Ryzen, often causing instability or lower speeds. A single 2x16GB kit gives dual-rank sticks for better performance and validated compatibility, while four sticks stress the memory controller and may force slower speeds. The cost difference is small, so sell the old kit or keep it as a backup to avoid BIOS headaches.