Actual artist is unknown, but this was sourced from someone on Twitter who had the following comment:

"AMD made Gijinka for their Ryzen processors. Supposedly they're on merch in Singapore. Ryfa and Zenka"
(https://twitter.com/Helios748/status/969727419551657984/photo/1)

I don't believe the tweeter is the artist. Might require a small investigation.

• [AKIBA PC Hotline!] (Japanese; Dec 4, 2017)
• [4Gamer.net] (Japanese; Nov 9, 2017)
• [PC Watch] (Japanese; Nov 1, 2017)

Swapped character tags Ryfa and Zenka due to how they're seen elsewhere. The tweet is misleading.

Meanwhile, fanart of these Ryzen girls is still miserably nonexistent.