Intel 5400 Series - Manual (Page 50)

Thermal/Mechanical Reference Design
50 Quad-Core Intel® Xeon® Processor 5400 Series TMDG
Clearance is required around the heatsink to ensure unimpeded airflow for proper
cooling. The physical baseboard keepout requirements for the active solution are the
same as the passive CEK solution shown in
Appendix B . Refer to Figure B-18 through
Figure B-20 for additional details on the active CEK thermal solution volumetrics.
2.5.8.1 Fan Power Supply
The active heatsink includes a fan, which requires a +12 V power supply. Platforms
must provide a matched fan power header to support the boxed processor.
Table 2-9
contains specifications for the input and output signals at the heatsink fan connector.
The fan outputs a SENSE signal, an open-collector output, which pulses at a rate of two
pulses per fan revolution. A baseboard pull-up resistor provides VCC to match the
baseboard-mounted fan speed monitor requirements, if applicable. Use of the SENSE
signal is optional. If the SENSE signal is not used, pin 3 of the connector should be tied
to GND.
It is recommended that a 4 pin fan header be used on the baseboard, in addition to, a
control ASIC that can send a PWM signal to the active fan heatsink solution on the 4
th
pin, at a nominal 25 KHz frequency. If a 3-pin CPU fan header is used instead, the
active fan heatsink solution will revert back to an automatic ambient air temperature
control mode.
The fan power header on the baseboard must be positioned to allow the fan heatsink
power cable to reach it. The fan power header identification and location must be
documented in the supplier’s platform documentation, or on the baseboard itself. The
baseboard fan power header should be positioned within 177.8 mm [7 in.] from the
center of the processor socket.
Note: System board should pull this pin up to V
CC
with a resistor.
Table 2-9. Fan Specifications (Boxed 4-wire PWM/DTS Heatsink Solution)
Description Min
Typ
Steady
Max
Steady
Max
Startup
Unit Notes
+12V: 12 Volt Fan Power
Supply
10.8 12 12 13.2 V
IC: Fan Current Draw N/A 1.25 1.5 1.5 A
SENSE: SENSE Frequency 2 2 2 2 Pulses per fan revolution 1
Figure 2-27. Fan Cable Connection (Active CEK)