Variable Width PCIe Interface for Modular Server Chassis
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Solution Overview
Problem
Existing systems for interfacing motherboards with expansion cards in rack-mounted servers face challenges in efficiently managing multiple expansion slots and optimizing the connection of various expansion cards to PCIe sockets, which can lead to complexity and reduced performance.
Innovation Solution
The proposed solution involves a chassis design with a midplane and motherboard sockets that allow for secure and flexible mounting of expansion cards, utilizing multiple PCIe sockets with detents for secure retention and a power supply system integrated into the midplane, along with a width detection module and lane configuration module for efficient PCIe interface management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple expansion slots are implemented in rack-mounted servers, then connectivity and functionality are improved, but system complexity and connection management difficulty increase
Solution Approach 1:
The PCIe interface is segmented into multiple independent lanes that can be independently configured and assigned. Each lane can be allocated to different expansion cards based on their width requirements (1x, 2x, 4x, 8x configurations), allowing flexible connection management without increasing overall system complexity
Solution Approach 2:
The system implements dynamic lane configuration where the motherboard can dynamically assign and reassign PCIe lanes to different expansion cards based on detected card width and performance requirements. This dynamic allocation simplifies connection management by automatically optimizing the mapping between physical slots and logical lanes
2Ease of manufacture
If fixed-width PCIe interfaces are used, then manufacturing is simplified, but adaptability to different expansion card sizes is reduced
Solution Approach 1:
The PCIe interface is divided into multiple standardized lane units that can be combined in different configurations. A single standardized lane design is manufactured, but these lanes can be assembled in various widths (1x, 2x, 4x, 8x) to accommodate different expansion card sizes, maintaining manufacturing simplicity while achieving versatility
Solution Approach 2:
The standardized PCIe lane unit serves multiple functions by being configurable in different widths. The same basic lane interface can support various expansion card types (1x, 2x, 4x, 8x) through flexible lane bonding and configuration, making the interface universal across different card sizes without requiring separate manufacturing for each configuration
3Device complexity
If traditional expansion slot designs are used, then structural simplicity is maintained, but securement reliability and connection stability are reduced
Solution Approach 1:
The chassis incorporates pre-positioned detents and retention mechanisms that automatically engage when an expansion card is inserted. These preliminary structural elements ensure secure card retention from the outset, improving reliability without requiring complex active securing mechanisms
Solution Approach 2:
The chassis acts as an intermediary structure between the motherboard and expansion cards, providing a standardized interface with integrated detents and retention features. This intermediary design simplifies the overall structure while ensuring reliable securement through the chassis-mediated connection mechanism
Data Source
AI summary
A chassis includes a midplane defining a plurality of expansion sockets on one side and one or more motherboard sockets on the other. A modular motherboard is removably inserted in the chassis and engages the one or more motherboard sockets. An expansion card may engage with one or more of the motherboard sockets simultaneously. The expansion sockets are arranged in a coplanar and collinear manner to enable a planar expansion card to simultaneously insert within multiple expansion sockets. The motherboard allocates lanes to the expansion card in response to detecting a number of sockets occupied by the expansion card.