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
Lexar ARES RGB DDR4 RAM 16GB Kit (8GB x 2) 4000 MHz, DRAM 288-Pin U-DIMM Desktop Memory, XMP 2.0 High Performance Computer Memory, CL18-22-22-42, PC4-32000, White (LD4EU008G-R4000GDWA) at Amazon.com
G.SKILL Conquers 4000MHz Speed Barrier and Releases New Trident Z and Ripjaws V Series DDR4 Memory - Designed for 6th Gen Intel Core Processors - G.SKILL International Enterprise Co., Ltd.
2666MHZ CL12 vs 4000MHZ CL19 - High RAM Speed or Low Latency ? - YouTube
CORSAIR VENGEANCE RGB PRO 16GB (2x8GB) DDR4 4000MHz C19 LED Desktop Memory - Black at Amazon.com
G.Skill Ripjaws V 32GB (2 x 16GB) DDR4 4000 MHz CL16 288-pin DIMM Black Memory (F4-4000C16D-32GVKA) - Bleepbox