iDRAC9: fan control for third-party PCIe cards on a Dell R740

Problem

After adding third-party PCIe cards to an R740, iDRAC9 ramped the fans to a constant high speed because it couldn't read temperature from the non-Dell cards and defaulted to a safe-but-loud fan response.

Cause

iDRAC's default "third-party PCIe card" thermal behaviour forces elevated fan speed whenever it detects a card it can't thermally monitor.

Fix

Set up management access, then disable the default third-party fan response with racadm:

• Install the iDRAC Service Module (iSM) so the OS and iDRAC can exchange sensor data; enable IPMI for sensor access.

• Use racadm to target the third-party fan response setting: racadm set system.thermalsettings.ThirdPartyPCIFanResponse 0

• Apply and confirm the fans settle to a normal curve; watch component temps for a while afterward to make sure nothing you care about runs hot with the override in place.

Only disable this if you're confident the added cards have adequate airflow — you're overriding a safety default.