Here's some memory that would work well with your motherboard:Unbuffered DDR3 memory
running at PC3-12800 (DDR3-1600) or faster, CAS 9 latency or less and 1.5 V or less voltage.
A couple of specific offers stand out:$45
2x4 GiB PC3-14900 G.Skill Ares F3-1866C9D-8GAB (DDR3-1866, CAS 9, 1.5 V)$56 -5½ code "VENGEANCEFEB1528"
2x4 GiB PC3-12800 Corsair Vengeance CML8GX3M2A1600C9B (DDR3-1600, CAS 9, 1.5 V)
i7-8700K, H100i v2, RoG Strix Z370-G Gaming, 16 GiB, RX Vega64, 960Pro SSD, 5TB HDD, Define Mini-C, SS-660XP2, C32HG70, RK-9000BR, MX518