How do I change or upgrade my STRIX HERO II RAM, what do I need to keep in mind?

[ArtemisWTF]

Hello guys,
I have a ROG STRIX HERO II and I was thinking upgrading my RAMM.

Currently I have this installed:
Module Size: 8 GBytes
Memory Type: DDR4 SDRAM
Module Type: SO-DIMM
Memory Speed: 1333.3 MHz (DDR4-2666 / PC4-21300)
Module Manufacturer: SK Hynix
Module Part Number: HMA81GS6CJR8N-VK

I have no idea what this is, but I was planning on buying 1 of these: HyperX Impact, 8GB, 2666MHz DDR4, CL15, SODIMM

Would this HyperX work with my current 8gb card? or do I need to buy a HyperX Kit of 2 (HX426S15IB2K2/32)?