HP rp7420, Service Manual, Page: 112 / 127

Each cell area fan cooling is controlled by a smart fan control board, embedded in the fan module
plastic housing. The smart fan control board receives fan control input from the system fan
controller on the system backplane and returns fan status information to the system fan controller.
The smart fan control board also controls the power and the pulse width modulated control
signal to the fan and monitors the speed indicator back from the fan. The fan status LED is driven
by the smart fan control board.
Bulk Power Supply Cooling
Cooling for the bulk power supplies is provided by two 60 mm fans contained within each BPS.
Air flows into the front of the BPS and is exhausted out of the top of the power supply through
upward facing vents near the rear of the supply. The air is then ducted out of the rear of the
chassis with minimal leakage into the cell airflow plenum.
PCI/Mass Storage Section Cooling
Six 92 mm fans located between the mass storage devices and the PCI card cage provide airflow
through these devices. The PCI fans are powered with housekeeping power and run at full speed
at all times. The air is pulled through the mass storage devices and pushed through the PCI Card
Cage. Perforation is provided between the PCI bulkheads to allow adequate exhaust ventilation
and to help reduce the localized airflow dead spots that typically occur at the faceplate tail of
each PCI card.
Standby Cooling
Several components within the chassis consume significant amounts of power while the system
is in standby mode. The system fans run at 1541 rpm, or 38% of full speed, during standby to
remove the resulting heat from the cabinet. The fans within the power supply operate at full
speed during standby.
Typical Power Dissipation and Cooling
Table B-5 Typical HP Integrity rx7620 server Configurations
Typical
Cooling Typical
Power Bulk Power
Supplies Core I/O Hard Disk
Drives DVDs PCI Cards
(assumes 10
watts each) Memory Per
Cell Board Cell
Boards
BTU/hr Watts Qty Qty Qty Qty Qty GBytes Qty
6930.42 2030 2 2 4 2 16 16 2
5916.46 1733 2 2 2 0 8 8 2
5728.69 1678 2 2 2 0 8 4 2
3574.46 1047 2 1 1 0 8 4 1
The air conditioning data is derived using the following equations.
•
Watts x (0.860) = kcal/hour
• Watts x (3.414) = Btu/hour
• Btu/hour divided by 12,000 = tons of refrigeration required
NOTE: When determining power requirements you must consider any peripheral equipment
that will be installed during initial installation or as a later update. See the applicable
documentation for such devices to determine the power and air-conditioning that is required to
support these devices.
Acoustic Noise Specification
The acoustic noise specification for the HP Integrity rx7620 server is 57.3 db (sound pressure
level at bystander position) It is appropriate for dedicated computer room environments but not
office environments. The LwA is 7.5 Bels. Be sure to understand the acoustic noise specifications
112 System Specifications