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SiS648 Ref Mainboard Gallery (3)
Overclocker 13 Jul 2002

The BIOS

The BIOS plays the most intrigue part of the system performance. In this reference board, we see that there are various settings that can be used to tune up the system performance. Do take note that when we talk about DDR266, DDR333, DDR400, we are referring to the memory speed. What is important is the ratio that is set to the CPU:MEM. For example, if you CPU is running the P4 533Mhz model, if you wish to run at DDR266, you could choose the option 1:1. Otherwise if you wish to run your RAM at DDR333 ASYNC mode, you set it to 4:5, DDR400 ASYNC at 2:3. How do you arrive at the ratios ? Very simple.

CPU : 133. To run at DDR 400, we use 133/200 (DDR400) and we get 2:3. For DDR333, we divide  133 by 166 (DDR333) and we arrive at 4:5. The following table summarises the various async settings available on SiS648 chipset. The FSB can be manually tuned from 100~255Mhz at 1Mhz stepping.

FSB

100Mhz

133Mhz

DDR 200

1:1

4:3

DDR 266

3:4

1:1

DDR 333

3:5

4:5

DDR 400

1:2

2:3

For example, if you would like SiS648 platform running CPU FSB533 and DDR 333, choose the Ratio 4:5.

This reference board comes with DDR timing which you could set it to AUTO or MANUAL mode. In our case, we set it to auto as we will use the other option to set the various timings at DDR333 Optimised, DDR400 Optimised and DRAM Performance to Normal, AUTO for DDR400, Fast, 1T for DDR333 , DDR266

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*specs are subjected to changes without notice

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