Abit IT5A User Manual page 25

Installing the Mainboard
IDT WinChip C6 CPU
IDT- External
WinChip Clock
C6
C6-200 66MHz 200MHz OFF ON
Cyrix/IBM 6x86MX CPU
Cyrix/IBM External
Clock
6x86MX
PR166 66MHz 133MHz ON
PR200 66MHz 166MHz ON
75MHz 150MHz ON
PR233 66MHz 200MHz OFF ON
75MHz 188MHz ON
83MHz 166MHz ON
PR266 66MHz 233MHz OFF OFF OFF OFF OFF ON
The turbo mode can be set when the CPU external clock can support.
The turbo mode will increase the external clock by about 2.5%. It is used to
verify the frequency tolerance at the design phase. It is very important for the
designer to conduct some tests. Please do not setup the turbo mode during
normal operation if you are not familiar with CPU architecture .
There are eight switches at SW2, DS1-DS3 are used to setup the rating
parameter and DS6-DS8 are used to setup the external clock. The following
tables present all of the adjustments for the setup combinations of CPU.
2.CPU Voltage and Setup (SW2)
For the voltage of the 586 series CPU, there are two kinds of operation
modes depending on the different CPUs; single voltage and dual voltage.
Please make sure what working voltage that you use before installation.
The following table presents all of the adjustments of voltage for all of the
586 series CPUs, Please setup the Vcore voltage for the CPU you are using.
For the Vio voltage will be 3.52V as VRE recommand for dual-voltage.
Internal External Clock
Clock Factor
DS1 DS2 DS3 DS4 DS5 DS6 DS7
Internal External Clock
Clock Factor
DS1 DS2 DS3 DS4 DS5 DS6 DS7
OFF OFF OFF OFF ON
ON
OFF OFF OFF OFF OFF ON
ON
OFF OFF OFF OFF OFF ON
Reserve External Clock
Frequency
OFF OFF OFF ON
Reserve External Clock
OFF OFF OFF ON
OFF OFF OFF ON
OFF OFF OFF OFF ON
DS8
ON OFF
Frequency
DS8
ON OFF
ON OFF
ON
ON OFF
ON
OFF
ON OFF
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