VIA Technologies P4MA PRO User Manual page 62

BIOS Setup
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.
Spread Spectrum
When the motherboard's clock generator pulses, the extreme values (spikes) of
the pulses creates EMI (Electromagnetic Interference). The Spread Spectrum
function 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 problems,
leave the setting at Disabled for optimal system stability and performance. But if
you are plagued by EMI, setting to Enabled for EMI reduction. Remember to
disable Spread Spectrum if you are overclocking because even a 0.25% jitter can
introduce a temporary boost in clockspeed of 25MHz (with a 1GHz CPU) which
Settings: Disabled, -1.
may just cause your overclocked processor to lock up.
50%, -1.00%,-0.70%,-0.50%,+/-0.75%,+/-0.50%,+/-0.35% and+/-0.
25%.
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