I recently assembled a PC in a Lian Li A3 case with a 9800X3D, 9070 XT, and a 240 mm AIO. Because the RAM is about 2 mm too tall, I couldn't mount the radiator on top without it pressing against the memory, so the AIO is currently mounted on the side as an intake. I also couldn't install all three planned bottom intake fans: the motherboard's front USB 3.0 connector blocks the middle position, and the GPU support bracket blocks the front position. The current layout is one bottom-rear intake, one rear exhaust, two top exhaust fans, and the side-mounted AIO intake.
The system is louder than expected, with a persistent hum and noticeable fan revving. Before adjusting the curves, the CPU repeatedly jumped between roughly 42°C and 60°C at idle, although a Windows update may have been running. After changing the ramp-up and ramp-down settings, idle temperatures are steadier at about 39°C. Startup briefly reaches around 65°C, and YouTube playback keeps it near 39°C. I haven't tested gaming yet. What fan curves or airflow changes would help reduce the noise and humming without causing temperature problems?
1 Answer
Try keeping the fans at a quiet fixed speed—around 25–35%—until the CPU reaches roughly 65°C. After that, use a gradual ramp rather than reacting to every small temperature spike, reaching around 50–60% near 85°C. There usually isn't a need to run the fans at full speed unless temperatures are genuinely high under load, such as over 90°C while gaming. If the humming remains even at a steady low speed, check whether it is coming from the pump or from a fan resonating against the case, since that would be a mechanical noise issue rather than an airflow problem.
Modern CPUs can briefly spike in temperature without being in danger. I generally keep fans below 80% and only let them approach that speed when the CPU is above about 90–93°C. A slower curve starting around 50°C should prevent the constant ramping, and maximum fan speed is usually where the noise becomes especially noticeable.