Thermally Advantaged Chassis

Lore & Background

The Thermally Advantaged Chassis specification was created by Intel. In version 1.1, the design is intended to disallow internal temperature rises of more than 3 degrees Celsius, providing the processor with a cooler environment to work in. Its main feature is a Chassis Air Guide that directs room temperature air directly in the path of the CPU fan and heat sink. The chassis air guide is a passive cooling system, relying completely on internal system fans to guide the air.

Airflow within the chassis follows a typical pattern: the rear fan and power supply fan exhaust, moving hot air away from the computer. This causes a slight depressurization inside the chassis, requiring all other openings to become intake vents. Airflow from the front of the chassis moves around the Chassis Air Guide, allowing the processor fan to only draw air from outside the chassis, providing more effective cooling.

The rear chassis exhaust fan is required to be at least 92 mm or larger, providing a minimum of 55 CFM in free air. The processor is required to have an active cooling system consisting of a fan and heat sink. The side panel is required to have an add-in card vent, which provides room temperature air to add-in cards; high-performance graphics cards benefit from the lower temperature air.

Reader's Guide

The Thermally Advantaged Chassis specification established a baseline cooling requirement for Intel's Pentium 4 (Prescott), Pentium D, and Celeron D processors. By mandating a Chassis Air Guide that draws outside air directly to the CPU cooler, the design addressed the higher thermal output of these processors. The requirement for a rear exhaust fan of at least 92 mm and 55 CFM ensured consistent airflow, while the side-panel add-in card vent provided cooling for high-performance graphics cards. Intel's position that a TAC is the absolute minimum requirement for using these processors underscored its importance in system reliability. The specification's focus on passive air guidance, combined with active CPU and chassis fans, represented a practical approach to thermal management without relying on liquid cooling or exotic materials. Its legacy lies in standardizing chassis design for higher-wattage CPUs, influencing how enclosures integrate airflow paths and fan placement.

Did You Know?

• The TAC specification requires the internal ambient temperature to stay below 38°C for Pentium 4 and Celeron D processors based on 90 nm technology.
• The Chassis Air Guide is a passive cooling system that relies entirely on internal system fans to direct air.
• The side panel must include an add-in card vent to supply room temperature air to graphics cards.