v-Color DDR4 128GB (2 x 64GB) Hynix IC 2933MHz(PC3-23400) R-DIMM for Apple Mac Pro 2019 ECC Registered DIMM Dual Rank 2Rx4 1.2V CL21 (VHA21ASDRAG4T-CG29RD) at Amazon.com
Mega Memory: Crucial Ships 128 GB DDR4-2666 Modules for Servers at $3999 per Unit