22.214.171.124. Single-Ended I/O Termination
Voltage-referenced I/O standards require an input VREF and a termination voltage (VTT). The reference voltage of the receiving device tracks the termination voltage of the transmitting device.
The supported I/O standards such as SSTL-12, SSTL-125, SSTL-135, and SSTL-15 typically do not require external board termination.
Intel recommends that you use OCT with these I/O standards to save board space and cost. OCT reduces the number of external termination resistors used.