Advanced Chipset Features
DRAM Clock
This item allows you to set the DRAM Clock. Options are Host CLK,
HCLK+33M or HCLK-33M. Please set the item according to the Host
(CPU) Clock and DRAM Clock.
SDRAM Cycle Length
This feature is similar to SDRAM CAS Latency Time. It controls the time
delay (in clock cycles - CLKs) that passes before the SDRAM starts to
carry out a read command after receiving it. This also determines the
number of CLKs for the completion of the first part of a burst transfer.
Thus, the lower the cycle length, the faster the transaction. However, some
SDRAM cannot handle the lower cycle length and may become unstable.
So, set the SDRAM Cycle Length to 2 for optimal performance if possible
but increase it to 3 if your system becomes unstable.
Bank Interleave
This feature enables you to set the interleave mode of the SDRAM
interface. Interleaving allows banks of SDRAM to alternate their refresh
and access cycles. One bank will undergo its refresh cycle while another
is being accessed. This improves performance of the SDRAM by mask-
ing the refresh time of each bank. A closer examination of interleaving will
reveal that since the refresh cycles of all the SDRAM banks are
staggered, this produces a kind of pipelining effect. If there are 4 banks in
the system, the CPU can ideally send one data request to each of the
SDRAM banks in consecutive clock cycles. This means in the first clock
cycle, the CPU will send an address to Bank 0 and then send the next
address to Bank 1 in the second clock cycle before sending the third
and fourth addresses to Banks 2 and 3 in the third and fourth clock
cycles respectively. Each SDRAM DIMM consists of either 2 banks or 4
banks. 2-bank SDRAM DIMMs use 16Mbit SDRAM chips and are
usually 32MB or less in size. 4-bank SDRAM DIMMs, on the other hand,
usually use 64Mbit SDRAM chips though the SDRAM density may be
up to 256Mbit per chip. All SDRAM DIMMs of at least 64MB in size or
greater are 4-banked in nature.
If you are using a single 2-bank SDRAM DIMM, set this feature to 2-
Bank. But if you are using two 2-bank SDRAM DIMMs, you can use the
4-Bank option as well. With 4-bank SDRAM DIMMs, you can use either
interleave options. Naturally, 4-bank interleave is better than 2-bank
interleave so if possible, set it to 4-Bank. Use 2-Bank only if you are
using a single 2-bank SDRAM DIMM. Notethat it is recommends that
SDRAM bank interleaving be disabled if 16Mbit SDRAM DIMMs are
used.
Memory Hole
Enabling this feature reserves 15MB to 16MB memory address space to
ISA expansion cards that specifically require this setting. This makes the
memory from 15MB and up unavailable to the system. Expansion cards
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