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Compaq W4000 User Manual

Page 84

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Chapter 4 System Support


High and low thermal parameters are programmed into the ASIC by BIOS during POST. If the

and the Therm-

signal will be asserted. The asserted Therm- signal can, with the proper software setup, be used by

NOTE: These systems do not support thermister-based fans used on earlier products.

high thermal parameter is reached then the fan(s) will be turned on full speed

the 82801 ICH2 to initiate an AOL message for transmission over a network (refer to Network
Interface Controller subsection in Chapter 5).



Fan Header












F

a

Control Block Diagram
















Figure 4

iagram

igure 4-11. Sm ll Form Factor Fan

Fan CMD

Fan


Control

C

ASI

Fan
Sense

SMBus

82801

Therm-

10

+5 VDC (+)

Interrupt

P1

Fan CMD

Processor

rol

IC

Cont

AS

Sink

Chassis
Fan Sense

(+)

2

SMBus

Therm-

2

CPU Fan Sense

+5 VDC

+5 VDC

82

ICH2

Power Supply Assembly

Speed

Control

SPD

Speed

Processor

(+)

(-)

ICH2

P1

13

PS Fan

Control

(-)

3

2

1

P70

Fan
Sink

PS

Circuits

+5 VDC

Power Supply Assembly

Speed

Control

Fan
SPD

PS

Circuits

(+)

(-)

Fan

(-)

3

1

Chassis Fan

Header P8

(-)
(+)

3

1

CPU Fan Header

P70

+5 VDC

12

24

PS Fan

801

-12. Desktop/Configurable Minitower Fan Control Block D

Compaq Evo and Workstation Personal Computers

Featuring the Intel Pentium 4 Processor

Second Edition – January 2003

4-30