64GB (4X16GB) DDR4-2666 PC4-21300 ECC UDIMM Compatible with Synology D4EC-2666-16G Memory Upgrade Module by NEMIX RAM at Amazon.com
CORSAIR VENGEANCE RGB PRO SL 64GB (4x16GB) DDR4 3600 (PC4-28800) C18 1.35V - White at Amazon.com
Kingston Technology 64GB RAM Kit (4x16GB) 2133MHz DDR4 ECC Reg CL15 DIMM DR x 4 with TS Server Memory (KVR21R15D4K4/64) at Amazon.com
G.Skill Trident Z RGB Series 64GB (2 x 32GB) 288-Pin SDRAM (PC4-28800) DDR4 3600 CL18-22-22-42 1.35V Dual Channel Desktop Memory Model F4-3600C18D-64GTZR at Amazon.com
OLOy DDR4 RAM 64GB (2x32GB) 2666 MHz CL19 1.2V 260-Pin Laptop Gaming SODIMM Upgrade for 2019/2020 iMac 27-inch with Retina 5K Display Late 2018 Mac Mini (MD4S322619MZDC) at Amazon.com
G.Skill RipJaws DDR4 SO-DIMM Series 64GB (2 x 32GB) 260-Pin SO-DIMM DDR4 3200 CL22-22-22-52 1.20V Dual Channel Memory F4-3200C22D-64GRS at Amazon.com