Acer ASPIRE Z3750 Service Manual page 29

Frequency/Voltage Control
Field
Enable Clock to All
DIMM/PCI
Spread Spectrum
Aspire Z3750 / Z3751 / Z5750 / Z5751 AIO Computer Service Guide
Description
When enabled, clock signals will be sent to the PCI and memory
slots regardless of whether the slot is occupied or not.
When the mainboard's clock generator pulses, the extreme values of
the pulses creates EMI (electromagnetic interference). Set this field
to Enabled to reduce this EMI level. This reduces interference
problems with other electronics in the area.
Note: Remember to disable the Spread Spectrum feature if you are
overclocking. A slight jitter can introduce a temporary boost in clock
speed causing the overclocked processor to lock up.
Value
Enabled
Disabled
Enabled
Disabled
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