I'd recommend getting a matching 8gb HyperX stick at 3200Mhz. 16gb total seems to be more than enough.
*To get 3200Mhz, you'll need to download Ryzen Master and choose the Auto-Overclock option and include the memory (Memory Clock and Fabric Clock set to 1600). Hit "Apply & Test" to get it working. This probably voids the HP warranty. You can see what speed your RAM is running at using Task Manager.