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Technical rules for system fans

Understanding the technical rules for system fans helps you install the correct type and number of fans based on what is configured for your server.

Fan redundancy rules​

  • Supported fan types:

    • Standard fan 4056 (21000 RPM)

    • Performance fan 4056 (28000 RPM)

  • Fan redundancy: N+1 redundancy, one redundant fan rotor

    • One processor: six hot-swap dual rotor system fans (one redundant fan rotor)

    • Two processors: eight hot-swap dual rotor system fans (one redundant fan rotor)

Note
The redundant cooling by the fans in the server enables continued operation if one rotor of a fan fails.

Fan selection rules​

The following lists the rules for selecting standard or performance fan.

Table 1. Fan selection rules for different conditions
UseIf your server meets any of the following conditions:
Standard or performance fanTDP <= 165 W
Performance fan

  • TDP > 165 W

  • Installed with the front 10 x 2.5'' AnyBay drive backplane or 16-EDSFF drive backplane

  • Installed with the 2 x 2.5'' rear backplane

  • Installed with any passive GPU

  • Installed with any of the following PCIe adapters:

    • ThinkSystem Broadcom 57454 10GBASE-T 4-port OCP Ethernet Adapter

    • ThinkSystem Broadcom 57508 100GbE QSFP56 2-port PCIe 4 Ethernet Adapter

    • Mellanox ConnectX-6 HDR100 IB/100GbE VPI 1-port x16 PCIe 3.0 HCA

    • Mellanox ConnectX-6 HDR IB/200GbE Single Port x16 PCIe Adapter

    • Mellanox ConnectX-6 HDR100 IB/100GbE VPI 2-port x16 PCIe 3.0 HCA

    • Mellanox ConnectX-6 Dx 100GbE QSFP56 2-port PCIe Ethernet Adapter

    • ThinkSystem Xilinx Alveo U50 100GbE 1-Port PCIe Gen4 Adapter

Note

  • Standard fans are enough for low-wattage processors while you can still use performance fans for better cooling.

  • If there is an OCP 3.0 Ethernet adapter installed, when the system is powered off but still plugged in to AC power, fans 1 and 2 will continue to spin at a much lower speed. This is the system design to provide proper cooling for the OCP 3.0 Ethernet adapter.