Chapter 4 System Support
Table 4-16. System Operational Status LED Indications
Table 4-16.
System Operational Status LED Indications
System Status
Power
LED
Hard Drive
LED
S0: System on (normal operation) Steady green Green w/HD activity
S1: Suspend Blinks green @ 1 Hz Off
S3: Suspend to RAM Blinks green @ 1 Hz Off
S4: Suspend to disk Blinks green @ 0.5 Hz Off
S5: Soft off Off - clear Off
Processor not seated Steady red Off
CPU thermal shutdown Blinks red @ 4 Hz [1] Off
ROM error Blinks red @ 1 Hz Off
Power supply crowbar activated Blinks red @ .5 Hz Off
System off Off Off
NOTE:
[1] Later systems using PCA#s 011305, 011308, or 011311 will power down for this condition.
4.7.4 THERMAL SENSING AND COOLING
All systems feature a variable-speed fan as part of the power supply assembly. All systems also
provide a system board connection for a processor’s heat sink-mounted fan (standard on all Small
Form Factor and on some Slim Desktop and Configurable Minitower units). Slim Desktop and
Configurable Minitower systems provide an auxiliary chassis fan. All fans are controlled through
temperature sensing logic both on the system board and in the power supply, with slight
differences between the Small Form Factor (Figure 4-11) and the Slim Desktop / Configurable
Minitower (Figure 4-12) systems.
An ASIC monitors a thermal diode internal to the processor and provides a Fan CMD signal that
the Speed Control logic uses to vary the speed of the fan(s) through the negative terminal of the
fan(s). The turning off of the fan(s) as the result from the system being placed into a Sleep
condition is initiated by the ASIC asserting the Fan Off- signal, which results in the On/Off
Control logic shutting off the +12 volts to the fan(s).
The main differences between the system types are as follows:
In the Small Form Factor system the processor fan (if installed) is controlled only by the
ASIC and not affected by a power supply thermal condition
♦
♦ In the Slim Desktop/Configurable Minitower systems all fans are speed-controlled by the
ASIC through the power supply so that a thermal condition of the processor or power supply
will affect all fans simultaneously.
Typical cooling conditions include the following:
1. Normal – Low fan speed.
2. Hot processor – ASIC directs Speed Control logic to increase speed of fan(s).
3. Hot power supply – Power supply increases speed of fan(s).
4. Sleep state – Fan(s) turned off. Hot processor or power supply will result in starting fan(s).
Compaq Deskpro and Evo Personal Computers
Featuring Intel Celeron and Pentium III Processors
Fifth Edition – March 2002
4-36
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