User Guide

Hardware Installation

2-24

Warning: Do not use SIMM and SDRAM DIMM together

unless you have 5V tolerance SDRAM (such as Samsung

or TI). The FPM/EDO operate at 5V while SDRAM

operates at 3.3V. If you combine them together the

system will temporary work fine; however after a few

months, the SDRAM 3.3V data input will be damaged by

5V FPM/EDO data output line.

There is an important parameter affects SDRAM performance, CAS Latency Time.

It is similar as CAS Access Time of EDO DRAM and is calculated as number of

clock state. The SDRAM that AOpen had tested are listed below. If your SDRAM

has unstable problem, go into BIOS "Chipset Features Setup", change CAS

Latency Time to 3 clocks.

Manufacturer Model Suggested

CAS Latency

Time

5V Tolerance

Samsung KM416511220AT-G12 2 Yes

NEC D4S16162G5-A12-7JF 2 No

Hitachi HM5216805TT10

2 No

TMX626812DGE-12

2 Yes

TMS626812DGE-15

3 Yes

TMS626162DGE-15

3 Yes

TMS626162DGE-M67

3 Yes

The driving capability of new generation chipset is limited because the lack of

memory buffer (to improve performance). This makes DRAM chip count an

important factor to be taking into consideration when you install SIMM/DIMM.

Unfortunately, there is no way that BIOS can identified the correct chip count, you

need to calculate the chip count by yourself. The simple rule is: By visual

inspection, use only SIMM with chip count less than 24 chips, and use only DIMM

which is less than 16 chips.