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The z990 eServer central electronic complex (CEC) houses four multichip-module-based processor units instead of one, as in the previous-generation z900 eServer. The multichip module (MCM) input/output pin density in z990 processor units is more than twice that of the MCMs in z900 processor units. This increase in packaging density and the consequent tripling of the current drawn by the processor units were accommodated by the first-time use of land grid array (LGA) MCM-to-board interconnections in an IBM zSeries eServer. This was done by using innovative refrigeration cooling of the MCM with air cooling as backup, and by a new mechanical packaging and power distribution scheme. This paper describes the mechanical engineering of the CEC cage, the LGA MCMto-board interconnection scheme, and the mechanical isolation of the MCM evaporator-heat-sink mass from the LGA contacts. The paper also describes the electrical power and the cooling solutions implemented to meet the more demanding requirements of the denser CEC package.

Modular server frame with robust earthquake retention Adequate retention of computer systems during earthquake events is important because it can not only prevent human injury and potential system damage, but also ensure system availability by limiting to acceptable levels the transmitted accelerations to critical system components such as hard drives. This paper discusses the design of an IBM frame structure and related hardware, and the retention methods used, to provide a robust mechanical installation in both raised-and nonraised-floor environments, capable of surviving severe seismic events. The development of the frame structure and the retention hardware involves extensive earthquake simulation testing, in which the responses of the system under different earthquake test profiles are recorded and analyzed in both the time and frequency domains. Industry standards such as the Bellcore NEBS GR-63-CORE and IBM internal specifications are reviewed and compared, and the transient responses of competing frame designs subjected to various earthquake profiles are investigated to ensure compliance. Finally, the concept of modular design, in which various frame components are utilized to create a flexible family of frames, is discussed.

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