Compaq ProLiant 8500 ProLiant 8500 Server Technology - Page 14

TC000604TB TECHNOLOGY BRIEF (cont.) ... The fan control logic operates independently from the system processor and OS. Regardless of which OS is running or its condition, the fan control logic and the server temperature monitoring circuitry work together to cool the server effectively. The fans have two speeds: normal and high. Under typical operating conditions, the normal fan speed is sufficient to cool up to 8 processors, 4 hard disk drives, and 11 I/O expansion boards. As a precaution against increases in ambient air or localized internal temperatures, Compaq established three thermal trip points, as shown in Figure 8. If the first thermal trip point is reached, the fans adjust automatically to high speed to increase cooling. Users can select whether to enable a server response to the second thermal trip point. When enabled, if the internal air temperature exceeds the second trip point, the OS initiates a controlled shutdown of the server. Simultaneously, a warning message is sent to the Integrated Management Display (IMD) and Compaq Insight Manager. The server restarts automatically when it has cooled sufficiently. Finally, in the unlikely event server temperature continues to rise, a third trip point shuts down the power supplies to protect critical components from overheating. The server restarts automatically when it has cooled sufficiently. System Boards - Hardware shutdown •-HRaredstart when cool •R es Power Supplies Ambient Probe Power Supplies - Graceful OS shutdown - System alert - Restart when cool Processors •S-pSepeed up fans •S y Temperature Monitoring Circuitry OS Fan Control Logic System Fans Figure 8: Schematic diagram of fan control logic. Redundant Processor Power Modules Each processor in the ProLiant 8500 server has its own redundant PPM. PPMs are also known as voltage regulator modules. An additional PPM is included in the server to power the system board. The PPMs deliver the precise voltage required by the processors. Compaq PPMs are programmable and support all current and future versions of Xeon processors. Each PPM has redundant circuitry. If a failure occurs in one circuit of the module, the other circuit automatically takes over the task of regulating power to the processor. 14