Intel 273246-002 Jumpers, Enable Spread Spectrum Clocking J14, Clock Frequency Selection J15

Hardware Reference

4.7Jumpers

Table 4-13shows default Jumper settings.

Table 4-13. Default Jumper Settings

Jumper	Function	Settings
J14	Enable Spread Spectrum Clocking	In – Enable Spread Spectrum
		Out – Disable Spread Spectrum (Default)
J15	Clock Frequency Selection	In – 66 MHz Processor Clock (Default)
		Out – Reserved
		1–2 Reserved
J20	On/Off	2–3 On (Default)
		No Jumper Installed – Off
J21	Flash BIOS VPP Select	1–2 12 V
		2–3 5 V (Default)
J22	Flash BIOS boot block control	1–2 12 V
		2–3 5 V (Default)
J23	SMI# Source	1–2 SMI# controlled by IOAPIC
		2–3 SMI# controlled by PIIX4E (Default)
J24	CMOS RAM Clear	1–2 Normal Operation (Default)
		2–3 Clear CMOS RAM

4.7.1Enable Spread Spectrum Clocking (J14)

This jumper is used to enable or disable spread spectrum clocking on the clock synthesizer. When this jumper is in, a 0.5% down spread will be introduced into the PCI and processor clocks. The default setting is no jumper installed, which disables spread spectrum clocking.

4.7.2Clock Frequency Selection (J15)

This jumper controls the frequency of the processor clock. When the jumper is in, 66 MHz operation is supported. This is the only setting supported by this evaluation kit.

Caution: Leave this jumper installed. When the jumper is out, 100 MHz processor clocks will be generated. This position is not supported and may cause damage to the processor.

4.7.3On/Off (J20)

This jumper is used to control the state of the ATX power supply. When this jumper is removed, the power supply will be turned off. Placing the jumper in the 2-3 position will turn the power supply on.

The 1-2 position is reserved and should not be used.

Celeron™ Processor Development Kit Manual 4-11