Intel Pentium 4 Processor with 512-KB L2 Cache on 0.13 Micron Process Thermal Design Guidelines

Intel Thermal Mechanical Reference Design Information
R
42 Intel
®
Pentium
®
4 Processor Thermal Design Guide
4.1 Intel Validation Criteria for the Reference Design
4.1.1 Acoustics
To optimize acoustic emission by the fan heatsink assembly, it is recommended to develop a
solution with a variable speed fan. It allows attaining thermal performance requirements at higher
fan inlet temperatures (T
A
) and lower noise at lower fan inlet temperatures. The required fan speed
necessary to meet thermal specifications can be controlled by the fan inlet temperature and should
comply with requirements below:
1. Fan set points
• High set point: T
A
= 42 °C; Ψ
CA
= 0.33 °C/W (per Table 3)
• Low set point: T
A
= 32 °C; Ψ
CA
= 0.46 °C/W
• Fan speed is linear between low set point and high set point.
2. Fan heatsink assembly acoustic performance:
• Acoustic performance is defined in terms of declared sound power (LwAd) as defined in
ISO 9296 standard, and measured according ISO 7779.
• LwAd does not exceed 5.7 BA at the high set point temperature.
• LwAd does not exceed 4.5 BA at the low set point temperature.
4.1.2 Altitude
The reference heatsink solutions will be evaluated at sea level. However, many companies design
products that must function reliably at high altitude, typically 1,500 m (5,000 ft) or more. Air-
cooled temperature calculation and measurement at sea level must be adjusted to take into account
altitude effects like different air density and overall heat capacity. This often leads to some
degradation in thermal solution performance compared to what is obtained at sea level, with lower
fan performance and higher surface temperatures. The system designer needs to account for this
altitude effects in the overall system thermal design to make sure that the T
C
requirement for the
processor is met at the targeted altitude.
4.1.3 Reference Heatsink Thermal Validation
The Intel reference heatsink is validated within specific boundary conditions based on the
methodology described in Section 3.3, using a thermal test vehicle (refer to Section 3.3.4).
Testing is done on bench-top test boards at ambient lab temperature. In particular, for the
3.06 GHz or higher reference heatsink, the Plexiglas* barrier is installed 3.2” above the
motherboard (refer to Section 3.3.2).
The test results are reported in terms of performance on real parts (using the thermal test vehicle
correlation), and of mean + 3σ value. See Table 5 for more information.