Intel 945G, 945GC, 945GZ, 945P, 945PL 4.1.2 Balanced Technology Extended (BTX) Form Factor Operating Environment

Reference Thermal Solution

20 Thermal and Mechanical Design Guidelines

Figure 5. Processor Heatsink Orientation to Provide Airflow to (G)MCH Heatsink on an

ATX Platform

Proc_HS_Orient_ATX

Airflow Direction

(G)MCH Heatsink

TOP VIEW

Omi Directional Flow

Processor Heatsink

(Fan Not Shown)

Other methods exist for providing airflow to the (G)MCH heatsink, including the use of

system fans and/or ducting, or the use of an attached fan (active heatsink).

4.1.2 Balanced Technology Extended (BTX) Form Factor Operating Environment

The operating environment for the (G)MCH in typical BTX systems has not been

profiled. This section provides operating environment conditions based on what has

been exhibited on the Intel micro-BTX reference design. On a BTX platform, the

(G)MCH obtains in-line airflow directly from the processor thermal module. Since the

processor thermal module provides lower inlet temperature airflow to the processor,

reduced inlet ambient temperatures are also often seen at the (G)MCH as compared to

ATX. An example of how airflow is delivered to the (G)MCH on a BTX platform is

shown in Figure 6.

The local ambient air temperature, TA, at the (G)MCH heatsink in the Intel micro-BTX

reference design is predicted to be ~45 °C. The thermal designer must carefully select

the location to measure airflow to get a representative sampling. These environmental

assumptions are based on a 35 °C system external temperature measured at sea

level.

Note: The local ambient air temperature is a projection based on anticipated power

increases on a 2005 platform and may be subject to change in future revisions of this

document.

Intel 4.1.2 Balanced Technology Extended (BTX) Form Factor Operating Environment