Solution:

If you install SRAM chips on the PCM-3810A, always set the "Battery backup" as "Enabled" to prevent battery power leakage. 1. Using Internal Battery Power: To use internal battery backup datas for SRAM you should have on-board battery when system power off. So you need to have short-cut on pin 2,3 of J8. 2. External Battery Connector: If you do not want the on-borad battery, on the other hand you need the external power supply to backup your datas on SRAM. Then you should have your SRAM on Bank 1 first and have 3.6~5 V on Pin 3 and GND to Pin 4 of J8.