HP dc7800 tower manual System Status, Thermal Sensing and Cooling

System Support

4.5.3 System Status

These systems provide a visual indication of system boot, ROM flash, and operational status through the power LED and internal speaker, as described in Table 4-8.

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Table 4-8.

System Operational Status LED Indications

System Status	PowerLED	Beeps [2]	Action Required
S0: System on (normal	Steady green	None	None
operation)
S1: Suspend	Blinks green @ .5 Hz	None	None
S3: Suspend to RAM	Blinks green @ .5 Hz	None	None
S4: Suspend to disk	Off – clear	None	None
S5: Soft off	Off – clear	None	None
Processor thermal shutdown	Blinks red 2 times @ 1 Hz [1]	2	Check air flow, fans, heatsink
Processor not seated / installed	Blinks red 3 times @ 1 Hz [1]	3	Check processor
			presence/seating
Power supply overload failure	Blinks red 4 times @ 1 Hz [1]	4	Check system board problem
			[3],
Memory error (pre-video)	Blinks red 5 times @ 1 Hz [1]	5	Check DIMMs, system board
Video error	Blinks red 6 times @ 1 Hz [1]	6	Check graphics card or
			system board
PCA failure detected by BIOS	Blinks red 7 times @ 1 Hz [1]	7	Replace system board
(pre-video)
Invalid ROM checksum error	Blinks red 8 times @ 1 Hz [1]	8	Reflash BIOS ROM
Boot failure (after power on)	Blinks red 9 times @ 1 Hz [1]	9	Check power supply,
			processor, sys. bd
Bad option card	Blinks red 10 times @ 1 Hz [1]	None	Replace option card

NOTES:

Beeps are repeated for 5 cycles, after which only blinking LED indication continues.

[1]Repeated after 2 second pause.

[2]Beeps are produced by the internal chassis speaker.

[3]Check that CPU power connector P3 is plugged in.

4.5.4Thermal Sensing and Cooling

All systems feature a variable-speed fan mounted as part of the processor heatsink assembly. All systems also provide or support an auxiliary chassis fan. All fans are controlled through temperature sensing logic on the system board and/or in the power supply. There are some electrical differences between form factors and between some models, although the overall functionally is the same. 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).

Technical Reference Guide www.hp.com 4-13