Patriot Viper Elite II DDR4 8GB(1 x 8GB) 4000MHz Single Memory Module at Amazon.com
G.Skill Trident Z NEO Series 32GB (2 x 16GB) 288-Pin SDRAM DDR4 4000 (PC4-32000) CL18-22-22-42 1.40V Dual Channel Desktop Memory Model F4-4000C18D-32GTZN at Amazon.com
G.Skill Trident Z RGB Series 16GB (2 x 8GB) 288-Pin SDRAM DDR4 4000 (PC4-32000) CL18-22-22-42 1.35V Dual Channel Desktop Memory Model F4-4000C18D-16GTZRB at Amazon.com
Crucial Ballistix MAX 4000 MHz DDR4 DRAM Desktop Gaming Memory Kit 16GB (8GBx2) CL18 BLM2K8G40C18U4B (BLACK) at Amazon.com
Corsair Vengeance RGB PRO SL 64GB (2x32GB) DDR4 4000MHz C18 Optimized for AMD Ryzen Desktop Memory (10 Ultra-Bright RGB LEDs, Custom Performance PCB, Tight Response Times, Intel XMP 2.0) Black at Amazon.com
G.Skill RipJaws V Series 16GB (2 x 8GB) 288-Pin SDRAM (PC4-32000) DDR4 4000 CL18-22-22-42 1.35V Dual Channel Desktop Memory Model F4-4000C18D-16GVK at Amazon.com