OWC 32GB (2x16GB) DDR4 2666MHz ECC UDIMM memory upgrade

Kit purpose

This 32 GB kit contains two 16 GB DDR4 2666 ECC UDIMM modules built for Synology RackStation RS3621RPxs and RS3621xs+ NAS units. It targets administrators who need to expand memory capacity for virtual machines, container workloads or large file caches on those specific models. The unbuffered ECC design matches the platform's requirement for error-correcting memory without registered signalling. Builders using other motherboards or consumer desktops should verify 288-pin DDR4 ECC UDIMM support before purchasing.

Physical fit

Each module uses a standard 288-pin UDIMM edge connector and operates at 1.2 V with CL19 latency. No heat spreader is fitted, so the sticks sit low enough for dense server chassis or narrow DIMM spacing. The 2Rx8 organisation is recognised by the RackStation firmware without manual configuration. Installers simply align the notch, press until the retention clips click, and the system detects the new capacity at the next boot.

Standard limits

The memory runs at DDR4 2666 (PC4-21300) and will down-clock automatically to 2400 MHz or 2133 MHz if the memory controller requires a lower data rate. JEDEC compliance guarantees electrical compatibility with any platform that accepts DDR4 ECC UDIMMs at those speeds. Total capacity is fixed at 32 GB across the two modules; systems needing more memory must populate additional slots with matching specifications.