RSMRST
Resume Well Reset: This signal is used for resetting the resume
power plane logic. This signal must be asserted for at least 10 ms after
the suspend power wells are valid. When deasserted, this signal is an
indication that the suspend power wells are stable.
从INTEL的南桥PDF里面复制出来的。意思就是南桥的待机电压准备好,告诉南桥可以开机。