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4-26
Chapter 4
4.10 Frequency/Voltage Control
CPU Clock Ratio
This setting controls the multiplier that is used to determine the internal clock
speed of the processor relative to the external or motherboard clock speed.
Auto Detect DIMM/PCI Clk
This option allows you to enable/disable the feature of auto detecting the clock
frequency of the installed DIMM/PCI bus. The settings are:
Enabled, Disabled
.
Spread Spectrum
When the motherboard’s clock generator pulses, the extreme values (spikes) of
the pulses creates EMI (Electromagnetic Interference). The Spread Spectrum func-
tion reduces the EMI generated by modulating the pulses so that the spikes of the
pulses are reduced to flatter curves. If you do not have any EMI problem, leave
the setting at
Disabled
for optimal system stability and performance. But if you
are plagued by EMI, activate the Spread Spectrum for EMI reduction. Remember
to disable Spread Spectrum if you are overclocking because even a slight jitter
can introduce a temporary boost in clockspeed which may just cause your
overclocked processor to lock up. Options:
Disabled, Enabled.
Summary of Contents for MEGA 651
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