HP D315 4.5SYSTEM CLOCK DISTRIBUTION

Technical Reference Guide

4.5SYSTEM CLOCK DISTRIBUTION

This system uses clock synthesizers in the IGP and the MCP or MCP-2 components. A 14.31818- MHz crystal provides an input for clock circuits of the MCP.

Table 4-10 lists clock signals that are distributed between system board components. Frequencies that are used only internally in chips and components are not listed.

Table 4-10.Clock Generation and Distribution

Table 4-10.

Clock Generation and Distribution

Frequncy	Source	Destination or Function
266 MHz	IGP	AGP feedback clock
200 MHz	IGP/MCP	Hyper Transport Bus clock
133 / 166 MHz [1]	IGP	Processor, DIMM sockets
66 MHz	IGP	AGP slot
33 MHz	IGP	APIC clock
32.768 MHz	Crystal	MCP, super I/O
25 MHz	Crystal	NIC PHY
25 MHz	NIC PHY	MCP
24.576 MHz	Crystal	Audio codec
16 MHz	IGP	APIC clock
14.31818 MHz	Crystal	MCP
14.31818 MHz	MCP	Clock buffer
14.31818 MHz	Clock buffer	IGP, super I/O
12.288 MHz	Audio codec	AC link clock

NOTE:

[1] D315 / d325

These systems uses the spread-spectrum feature of the IGP component. This feature allows BIOS to set a down spread (0.9 % on the D315, 0.5 % on the d325) to lower the possible effects of high frequency EMI. Clocks affected by the spread include those used by the processor, memory, and AGP.

Compaq D315 and hp d325 Personal Computers4-21

Featuring the AMD Athlon XP Processor

Second Edition - April 2003