Instruction manual

3-11
BIOS Setup
set this field to [Manual], the following fields will be selectable. The settings are:
[Auto], [Manual].
Memclock index value (Mhz)
When Timing Mode is set to [Manual], user can place an artificial memory
clock on the system. Please note that memory is prevented from running faster
than this frequency.Setting options: [100MHz] ~ [200MHz].
CAS# Latency (Tcl)
When the Timing Mode is set to [Manual], the field is adjustable.This controls
the CAS latency, which determines the timing delay (in clock cycles) before
SDRAM starts a read command after receiving it. Settings: [Auto], [2.0], [2.5], [3.
0]. [2.0] increases the system performance the most while [3.0] provides the
most stable performance.
Min RAS# Active Time (Tras)
When the Timing Mode is set to [Manual], the field is adjustable. This setting
determines the time RAS takes to read from and write to a memory cell. Setting
options: [Auto], [5T] ~ [15T].
RAS# to CAS# delay (Trcd)
When the Timing Mode is set to [Manual], the field is adjustable. When DRAM
is refreshed, both rows and columns are addressed separately. This setup
item allows you to determine the timing of the transition from RAS (row address
strobe) to CAS (column address strobe). The less the clock cycles, the faster
the DRAM performance. Setting options: [Auto], [2T] ~ [7T].
Row Precharge Time (Trp)
When the Timing Mode is set to [Manual], the field is adjustable. 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. Setting options: [Auto], [2T] ~ [7T].
Row cycle time (Trc)
When the Timing Mode is set to [Manual], the field is adjustable. The row
cycle time determines the minimum number of clock cycles a memory row takes
to complete a full cycle, from row activation up to the precharging of the active
row. Setting options: [Auto], [7T] ~ [22T].
Row refresh cyc time (Trfc)
When the Timing Mode is set to [Manual], the field is adjustable. This setting
indicates Auto refresh or CAS Before RAS (CBR). DRAM needs to refresh
periodically in order to retain its data which can be done by an internal counter
/ scheduler and a so-called CBR command. The auto refresh time used to take
the same number of cycles as a standard bank cycle, however, with increased
DRAM densities, oftentimes now two consecutive rows are refreshed back to