The case fan operates at maximum velocity.
The case fan operates at maximum velocity.
I think the issue might be with how the fans are connected. One uses a three-pin port while the other a four-pin. You could use a splitter to combine the four-pin into a three-pin, but make sure it matches the fan's requirements.
The case fan for chassis 2 isn't listed in the BIOS settings. Just chassis 1 is available, and it's operating at standard speeds.
It seems the 2nd chassis fan is marked as "PWR FAN." That means it operates continuously at 12V and isn’t managed through BIOS settings. This behavior likely accounts for the issue you’re experiencing.