Intel PT-6IBT User Manual page 33

440BX/ZX AT
HOW TO DECIDE THE CPU SPEED:
Basically, there are two parameters which will decide the CPU speed - the Front
Side Bus (FSB) speed and CPU clock ratio. When you have installed the processor
on the mainboard, the system BIOS will detect the CPU type and decide the FSB
speed automatically (please refer to section 4-6 "
the clock ratio, the setting of clock ratio will be different on Pentium™ II,
Pentium™ III and Celeron™ processors, Please refer to following for details:
Celeron™ Processor:
The clock ratio is fixed for Celeron™ processor, it means that we can not select
different clock ratio to what is defined by Intel. So we will be unable to select other
clock ratio for the Celeron™ processor. In other word, the clock ratio switch
setting mentioned earlier in this chapter will make no change to the clock ratio.
Once you have installed the Celeron™ processor onto the mainboard, the clock
ratio is decided already. So all we can do is use the BIOS setup program (or JP100)
to select the FSB clock for the CPU. Basically, "Default" setting is recommended
because it will detect the CPU type and select the proper FSB clock for the CPU.
When "Default" is selected in the BIOS setup program, you don't have to do any
setting when installing the Celeron™ processor. Simply plug and play immediately
( Of course, you can select other FSB clock for the Celeron™ processor and the
performance will be different to the "Default" setting. )
Pentium™ II Processor:
If you are installing the Pentium™ II or Pentium™ III processor onto the
mainboard, you will have to use the switch setting to select CPU clock ratio. The
following formula is the simple rule to calculate your CPU frequency:
FSB Clock x Clock Ratio = CPU Frequency
SELECTING THE FSB CLOCK ( please refer to section 4.6 )
Most of the time, you don't have to do anything to select the FSB clock, because
the system BIOS will do the job for you. ( unless you use JP100 to select your own
FSB clock)
MAINBOARD
AWARD BIOS SETUP
CPU Host Clock (CPU/PCI)"
3-19
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