HP 9000 rp4410-4 User Service Guide, Fifth Edition - HP 9000 rp4410/4440 - Page 47

board. Data from the sensor is used to control the fan speed and to initiate system overtemperature shutdown. Nonoperating Environment The system is designed to withstand ambient temperatures between -40°C to 70°C under nonoperating conditions. Cooling This section provides information on the cooling systems in the server. CPU and Memory Cooling The server incorporates front to back airflow across the processor and memory extender boards and through the HDD backplane. Two 127 mm dual fan assemblies, mounted vertically in the center of the chassis, pull air through the processor and memory section and push air through the PCI section. Each processor and memory dedicated dual fan assembly is controlled by smart fan control circuits embedded in the system I/O board. The smart fan control circuit receives fan control input from the system fan controller in the I/O board, and returns fan status information to the system fan controller. The smart fan circuit controls the power and the pulse-width-modulated control signal to the fan and monitors the speed indicator back from each of the fans. The fan status LED is driven by the smart fan circuit. The fan status LED is located on the diagnostic board inside the system. Bulk Power Supply Cooling Cooling for the bulk power supplies is provided by one 120 mm dual fan assembly and one externally mounted 60 mm power supply fan. Air is pushed into both power supply bays by the 120 mm fan assembly and exhausted out the rear by the 60 mm fan (one per power supply). Air flows out of the rear of the chassis with minimal leakage into the cell airflow plenum. NOTE: A power supply filler is required in the unused power supply slot to maintain proper airflow throughout the system. PCI and Mass Storage Section Cooling Two dual fan assemblies located at the center of the chassis provide airflow for all the PCI slots. Air flows over the processor and memory extender boards and into the PCI section. The fans are controlled by the system temperature and run at the speed necessary to maintain proper internal temperature throughout the chassis. The air is pulled through openings in the front cover and the mass storage devices and is pushed through the PCI card cage. Perforations between and above the PCI card cage enable proper exhaust ventilation to maintain the required temperature rating of the PCI cards. CAUTION: For maximum cooling effects, ensure that the chassis ventilation holes are not blocked or covered after installation. Figure 2-1 shows the airflow through the server. Environmental Specifications 47