I recently ordered parts for a compact PC build in a Lian Li A3 case, using a Ryzen 7 9800X3D with an AIO cooler and a Radeon RX 9070 XT. Although the parts passed a compatibility check, several fit issues changed my planned airflow layout.
I originally intended to mount the 240 mm AIO at the top as exhaust, but the RAM is about 2 mm too tall and interferes with the radiator. I mounted the AIO on the side as an intake instead. I also planned to use three bottom intake fans, but the motherboard's front USB 3.0 connector blocks the middle position and the GPU support bracket blocks the front position. At the moment, I only have one 120 mm bottom intake fan, along with one 120 mm rear exhaust fan and two 120 mm top exhaust fans.
The system is louder than expected, with a persistent humming sound and noticeable fan revving. I adjusted the fan curves and ramp-up/ramp-down settings, which helped somewhat. Initially, the CPU temperature repeatedly fluctuated between 42°C and 60°C at idle, possibly because Windows was updating. It now sits around 39°C at idle, briefly reaches about 65°C during startup, and stays near 39°C while watching YouTube. I have not tested it under gaming or heavier workloads yet.
Could the unusual airflow arrangement be causing the noise, or should I focus mainly on tuning the fan curves and identifying which component is producing the hum?
1 Answer
A quieter approach is to keep the fans at a fairly steady low speed instead of letting them react aggressively to every small temperature change. For example, you could hold them around 25–35% until the CPU reaches roughly 65°C, then gradually increase them to about 50–60% by 85°C. There usually is not much benefit to running fans near maximum unless temperatures are actually getting too high under load. Fan speeds above roughly 80% are often where the noise becomes especially noticeable.
That makes sense. I adjusted the curve and the constant revving has already improved, so I’ll try a slower ramp and lower maximum speed as long as temperatures remain safe.