Intel® Pentium® Silver and Intel® Celeron® Processors Datasheet, Volume 1
GPIO Buffer Impedance Compensation via SD3_RCOMP
All GPIO buffers require impedance compensation for 1.8 V and 3.3 V operation. The impedance compensation is done via the SD3_RCOMP signal. Therefore, SD3_RCOMP signal must have a precision pull down resistor of 200 Ohm (1 %) to GND (regardless of SDXC being used or not). Without proper impedance compensation, the GPIO buffers, including the muxed native functions, may not operate as expected.