1 x 4GB DDR4-2133 PC4-17000 SKHynix original RAM Upgrade Non-ECC 1.2 Volt 260 Pin SK hynix Unbuffered Small Outline DDR4 SDRAM DIMMs (Unbuffered Small Outline Double Data Rate Synchronous DRAM Dual In-Line Memory Modules) are low power, high-speed operation memory modules that use DDR4 SDRAM devices. These Unbuffered DDR4 SDRAM Unbuffered Small Outline DIMMs are intended for use as main memory when installed in systems such as micro servers and mobile personal computers.