Qnap 4 GB Accessories RAM-4GDR4ECP0-UD-2666, 4 GB, DDR4 SDRAM, 1.20 V, Speed 2666 MHz, DDR4-2666/PC4-21333, 288-pin, FF DIMM, QNAP TS-983XU Enterprise NAS Server. The 4GB DDR4 2666 MHz UDIMM ECC Memory Module from QNAP is a single RAM module that will let you upgrade the overall memory capacity of your compatible NAS. It features a capacity of 4GB, a clock speed of 2666 MHz (PC4-21300).