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NVIDIA® Uses Compact Thermal Models to Speed Design of NVIDIA nForceTM 4-based Systems

A composite picture of an NVIDIA nForceTM4 chip, showing temperature simulation (left side) and the chip's regular colors (right side)

September 2005

NVIDIA® took advantage of the speed and time savings provided by compact thermal models to reduce the time required to optimize package design and develop thermal design guidelines for their new NVIDIA nForceTM4 media and communications processor. NVIDIA optimizes the package design of its products in order to improve thermal performance and minimize real estate and also provides its customers with detailed thermal guidelines that simplify system design.

NVIDIA has developed a new process that substantially reduces the amount of time required to simulate the thermal performance of new products. The new process uses the web-based "FloTHERM.PACK" software from Flomerics to quickly produce a computationally-efficient thermal behavioral model - known as a "compact" model - which accurately represents a component's thermal characteristics in any end-user environment.

"We simply describe the die size and heat dissipation and the package characteristics, such as substrate size and number of balls, in the FloTHERM.PACK web site and hit go," said Mark Hemmeyer, Mechanical Engineer for NVIDIA. "Then the web-site generates a compact thermal model that predicts the temperature of the various elements within the package accurately regardless of the computational environment in which it is placed."

For a typical version of the NVIDIA nForce4, Hemmeyer evaluated a number of different packages with the goal of optimizing the design by trading off the thermal performance against package size. "This process used to take at least a week when we modeled the full geometry of the package and die. The new approach makes it possible to do a thorough thermal performance evaluation well in advance of first silicon. Only minimal physical testing is required to confirm the accuracy of the simulation during the time-sensitive later stages of the development cycle."

Hemmeyer also prepared a thermal design guide that provides answers to questions such as whether or not a heatsink is required under certain ambient temperature and airflow conditions and what type of heatsink provides the best performance. To obtain this type of detailed thermal performance information, Hemmeyer downloaded both the "two-resistor" and "Delphi" compact models for the final package from the FloTHERM.PACK website and imported them into FloTHERM thermal simulation software. In the FloTHERM environment, he developed various reference mechanical designs based on chip's target market, which is high-end desktop systems.

"Within FloTHERM I can play with a various environments and look at the impact on junction temperatures as the airflow across the chip is reduced," Hemmeyer said. "In the case of the NVIDIA nForce4, I first evaluated a number of different active and passive heatsinks and picked one from each category that provided the best performance. Then I evaluated the chip under different operating speeds, airflows, and board conditions with no heatsink, a passive heatsink, and an active heatsink. By the time I was done, I was able to provide a detailed engineering document that makes it clear to our customers what is required to keep the chip cool under a wide range of conditions."

Reviewers have lauded the NVIDIA nForce4's firsts, including NVIDIA "ActiveArmor", which provides end users with a hardware-accelerated security firewall solution built directly into the silicon; support for the next-generation SATA 3Gb/s hard drives; native Gigabit Ethernet networking, and advanced overclocking options through the use of the Company's nTune software application.

For further information, please contact:

Nazita Saye
Head of Marketing
Mentor Graphics Mechanical Analysis, UK
81 Bridge Road
Hampton Court
Surrey, KT8 9HH

Tel: +44 (0)20 8487 3000
Fax: +44 (0)20 8487 3001

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