Synology RAM DDR4 ECC SO-DIMM 8GB (D4ES01-8G) at Amazon.com
parts-quick 8GB Memory for Dell OptiPlex 7040 SFF DDR4 PC4-17000 Non-ECC DIMM RAM at Amazon.com
G.Skill Trident Z RGB Series 16GB (2 x 8GB) 288-Pin SDRAM (PC4-25600) DDR4 3200 CL16-18-18-38 1.35V Dual Channel Desktop Memory Model F4-3200C16D-16GTZR at Amazon.com
Amazon.com: Transcend 8GB JM DDR4 2666 SO-DIMM 1Rx8 1.2V (JM2666HSB-8G)
Timetec 8GB DDR4 2666MHz PC4-21300 Non-ECC Unbuffered 1.2V CL19 1Rx8 Single Rank 288 Pin UDIMM Desktop PC Computer Memory RAM Module Upgrade (8GB) at Amazon.com