First you need to make sure IPMI Over LAN is enabled in Idrac setting. Go to Idrac settings -> Network -> IPMI Settings, enable the configuration and leave other settings.

Get a system which has Impitool, for me i used linux subsystem under Windows and it works great, but any other system should also works. Get into the shell using Windows Terminal, for me its an Ubuntu subsystem so i just need to

1sudo apt update
2sudo apt install ipmitool
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Then we need to enable fan control manual mode by

1ipmitool -I lanplus -H idracIpAddress -U yourUsername -P yourPassword raw 0x30 0x30 0x01 0x00
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You can also disable it anytime using

1ipmitool -I lanplus -H idracIpAddress -U yourUsername -P yourPassword raw 0x30 0x30 0x01 0x01
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With manual control mode enabled, we can run following command to control the fan speed

• 0% Fan Speed

1ipmitool -I lanplus -H idracIpAddress -U yourUsername -P yourPassword raw 0x30 0x30 0x02 0xff 0x00
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• 5% Fan Speed

1ipmitool -I lanplus -H idracIpAddress -U yourUsername -P yourPassword raw 0x30 0x30 0x02 0xff 0x05
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• 10% Fan Speed

1ipmitool -I lanplus -H idracIpAddress -U yourUsername -P yourPassword raw 0x30 0x30 0x02 0xff 0x0A
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• 20% Fan Speed

1ipmitool -I lanplus -H idracIpAddress -U yourUsername -P yourPassword raw 0x30 0x30 0x02 0xff 0x14
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• 30% Fan Speed

1ipmitool -I lanplus -H idracIpAddress -U yourUsername -P yourPassword raw 0x30 0x30 0x02 0xff 0x1e
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Just need to change the last parameter to the fan speed percentage to hex so 50% would be 0x32

When done you can use the following command line to read the current fan speed

1ipmitool -I lanplus -H idracIpAddress -U yourUsername -P yourPassword sensor reading "Fan1A" "Fan1B" "Fan2A" "Fan2B" "Fan3A" "Fan3B" "Fan4A" "Fan4B"
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Change the fan name in quote to what you read from Idrac fan list.

For 720xd, run

1racadm set system.thermalsettings.FanSpeedOffset 255
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