Synology RS4021xs+ 16 Bay NAS Intel Xeon D-1541 8-core 2.1 16G DDR4 UDIMM Hot Swappable 2 x Gen3 x8 slots 3U 2 xUSB3.2

The 16-bay RS4021xs+ provides solid data security and lightening-fast performance with over 234K 4K random read IOPS and 6,258 MB/s sequential read throughput1. Together with its 8-core processor, ECC memory, advanced snapshot technology, and built-in 10GbE connectivity, the RS4021xs+ can support large multi-user environments while handling data-intensive workloads.

CPU Model Intel Xeon D-1541
CPU Architecture 64-bit
CPU Frequency 8-core 2.1 (base) / 2.7 (turbo) GHz
Hardware Encryption Engine (AES-NI)
System Memory 16 GB DDR4 ECC UDIMM
Total Memory Slots 4
Maximum Memory Capacity 64 GB (16 GB x 4)
Maximum Drive Bays with Expansion Unit 40 (RX1217/RX1217RP x 2)
Hot Swappable Drive
RJ-45 1GbE LAN Port 4 (with Link Aggregation / Failover support)
RJ-45 10GbE LAN Port 2 (with Link Aggregation / Failover support)
USB 3.2 Gen 1 Port* 2
PCIe Expansion 2 x Gen3 x8 slots (x8 link)
Form Factor (RU) 3U
Rack Installation Support* 4-post 19' rack (Synology Rail Kit - RKS1317) not included
System Fan 80 mm x 80 mm x 3 pcs

Mention: If NAS use over 8TB HDD, please only chose Synolgy Brand HDD
https://www.synology.com/en-global/compatibility