MSI 651M-V Instruction Manual page 16

CPU Clock Ratio
End users can overclock the processor (only if the processor supports so) by specifying the CPU ratio
(clock multiplier) in this field. It is available only when Set CPU Ratio is set to [Manual].
Auto Detect DIMM/PCI Clk
This item is used to auto detect the PCI slots. When set to [Enabled], the system will remove (turn off)
clocks from empty PCI slots to minimize the electromagnetic interference (EMI). Settings: [Enabled],
[Disabled].
Spread Spectrum
When the motherboard 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 problem, leave the setting at [Disabled] for optimal system stability and performance. But if you
are plagued by EMI, set to [Enabled] for EMI reduction. Remember to disable Spread Spectrum if you
are overclocking because even a slight jitter can introduce a temporary boost in clock speed which may
just cause your overclocked processor to lock up.
CPU Frequency
Use this item to select the appropriate clock frequency of the CPU host bus. Options are: [100MHz],
[133MHz], [Default].
DRAM Frequency
Use this item to select the appropriate frequency for your DDR SDRAM modules. Options are:
[200MHz], [266MHz], [333MHz] and [By SPD].
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