Figure 60. Temperature Range = 5 °C - Intel QX9770 - Core 2 Extreme Quad-Core Processor Design Manual

Legacy Fan Speed Control
Figure 60. Temperature Range = 5 °C
An alternate would be to consider a slightly larger value such as T
this case the design is trading off the acoustic margin for thermal margin.
• There is increased granularity in the fan speeds.
• Fan speed oscillation are significantly reduced
• Maximum fan speed is lower
The rate of change of Ψ
the beginning of the fan acceleration than as the maximum speed is approached. By
having the fan start to accelerate at a lower T
keep up with rate of change in processor power. The rate of change in acoustics
(dBA) is more linear with RPM. When comparing these two metrics the choice of a
larger T
RANGE
at the same conditions as in Figure 60 but T
Thermal and Mechanical Design Guidelines
Fan RPM
3500
3000
2500
2000
1500
1000
500
0
vs. RPM is an exponential curve with a larger decrease at
CA
value becomes a more acceptable trade off. Figure 61 graphs the system
Tdiode Tcontrol
Time (s)
reading the thermal solution can
SENSOR
= 10°.
RANGE
Tlow
80
75
70
65
60
55
50
45
40
= 10 °C. In
RANGE
101