Heatsink Performance; Acoustics; Table 2. Intel Liquid Cooled Reference Design Performance (Alct); Table 3. Acoustic Results - Intel QX9770 - Core 2 Extreme Quad-Core Processor Design Manual

5.1.1

Heatsink Performance

Table 2 provides the Intel ALCT Reference Design performance for the Intel
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
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 , of 3 °C. Meeting T
R
(refer to Sections 2.2, 2.4. and Chapter 4). Minimizing T

acoustics.

Table 2. Intel Liquid Cooled Reference Design Performance (ALCT)

®
Intel Core™ 2 Extreme processor QX6800 B3 stepping
®
Intel Core™ 2 Extreme processor QX9770 C0 stepping
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)
100%
(3300)
25%
(900)
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.
40
assumption of 38 °C for the Intel reference thermal
A
and Ψ targets can maximize processor performance
A
CA
Processor
Pump Speed Acoustic
PWM
(RPM)
100% 6.0BA
(1700)
25% 3.6BA
(600)
LGA775 Socket Heatsink Loading
, can lead to improved
R
Target Thermal
Performance, Ψca
(Mean + 3σ)
0.13 °C/W
0.13 °C/W
Thermal Descriptions
Performance
Ψca
0.13 °C/W Maximum fan and pump
speed
~0.23 °C/W Minimum fan and pump
speed
Thermal and Mechanical Design Guidelines
®
Core™2
T
A
Assumption
= 38 °C
T
A
= 38 °C
T
A