Just done a similar exercise to two HP Microserver Gen8 using the following (Timetec Hynix IC 16GB Kit(2x8GB) DDR3L 1600MHz PC3-12800 Unbuffered ECC 1.35V CL11 2Rx8 Dual Rank 240 Pin UDIMM Server Memory) from Amazon @ $85USD https://www.amazon.com/dp/B00KAGU1X0?ref=ppx_pop_mob_ap_share

Both boxes (Unraid and Centos respectively) have been running for about a week with the RAM and no issue and HP System/Bios recognise it without any issues on boot.

Did start with Kingston/crucial, but could not find any cheap enough due to server grade RAM and DDR3.

edit: added price paid.