Foxconn NF4UK8AA series User Manual page 44

Min RAS# active time (Tras) (Default: Auto)
This item determines the time RAS takes to read from and write to a memory cell.
Row Precharge Time (Trp) (Default: Auto)
This item controls the number of cycles for Row Address Strobe (RAS) to be
allowed to precharge. If insufficient time is allowed for the RAS to accumulate
its charge before DRAM refresh, refreshing may be incomplete and DRAM may
fail to retain data. This item applies only when synchronous DRAM is installed
in the system.
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Chapter 3 BIOS Description