LGA775 Socket Heatsink Loading
40
Thermal and Mechanical Design Guidelines
5.1.1
Heatsink Performance
Table 2 provides the Intel ALCT Reference Design performance for the Intel
®
Core™2
Extreme processor QX6800 B3 Stepping and QX9770 C0 Stepping. The results are
based on the test procedure described in Section
5.1.4.
The table also includes a T
A
assumption of 38 °C for the Intel reference thermal
solution at the inlet to the heat exchanger fan discussed in Section
3.3. An external
ambient temperature to the chassis of 35 °C is assumed, resulting in a temperature
rise, T
R
, of 3 °C. Meeting T
A
and
Ψ
CA
targets can maximize processor performance
(refer to Sections
2.2,
2.4. and Chapter
4). Minimizing T
R
, can lead to improved
acoustics.
Table 2. Intel Liquid Cooled Reference Design Performance (ALCT)
Processor Target
Thermal
Performance,
Ψ
ca
(Mean + 3
σ
)
T
A
Assumption
Intel
®
Core™ 2 Extreme processor QX6800 B3 stepping
0.13
°
C/W T
A
= 38
°
C
Intel
®
Core™ 2 Extreme processor QX9770 C0 stepping
0.13
°
C/W T
A
= 38
°
C
5.1.2
Acoustics
To optimize acoustic emission by the heat exchanger fan and pump, the reference
design implements a variable speed fan and pump. A variable speed fan and pump
allows the reference design performance to adjust for changes in processor utilization
and ambient air conditions. The required fan speed necessary to meet thermal
specifications can be controlled by the silicon sensor temperature and should comply
with requirements in Table 3.
Table 3. Acoustic Results
Fan Speed
PWM
(RPM)
Pump Speed
PWM
(RPM)
Acoustic Thermal
Performance
Ψ
ca
Descriptions
100%
(3300)
100%
(1700)
6.0BA 0.13
°
C/W
Maximum fan and pump
speed
25%
(900)
25%
(600)
3.6BA ~0.23
°
C/W
Minimum fan and pump
speed
NOTES:
1.
Acoustic performance is defined in terms of measured sound power (LwAm) as defined in
ISO 9296 standard, and measured according to ISO 7779.
2.
Pump speed represents 3 pulses per rotation and if read by MB circuitry that assumes 2
pulses per rotation. It will perceive its operating (rotating) faster than specified in the table
(e.g., the real pump speed is 600 rpm, 3 pulses, but MB would report 900rpm per 2 pulses
calculated.)
3.
If only 3 pin headers are available on MB that operate at a constant 12 V, the fan and
pump will operate at full speed and this condition does not represent the minimum speed.
The design is intended to run using 4 pin header PWM signals specified in Sections
5.1.5
and
5.1.6.
4.
If only one 4 pin header is available on MB (all others are 3 pin headers), it is
recommended to run the pump off of the 4 pin header and the fan off of the 3 pin header
and to have both headers respond to the CPU temperature to deliver the performance
indicated in Table 3.
Summary of Contents for QX68000 Core 2 Extreme
Page 30: ...LGA775 Socket Heatsink Loading 30 Thermal and Mechanical Design Guidelines...
Page 74: ...Heatsink Clip Load Metrology 74 Thermal and Mechanical Design Guidelines...
Page 76: ...Thermal Interface Management 76 Thermal and Mechanical Design Guidelines...
Page 96: ...Case Temperature Reference Metrology 96 Thermal and Mechanical Design Guidelines...
Page 108: ...Legacy Fan Speed Control 108 Thermal and Mechanical Design Guidelines...
Page 112: ...BTX System Thermal Considerations 112 Thermal and Mechanical Design Guidelines...
