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Why Are My AIO Fans So Loud at Idle?

September 21, 2026 3 answers
Asked by MellowPine47
I just built my first PC, and the fans are much louder than expected even when the system is idle. The Arctic Liquid Freezer III Pro 360 AIO seems to be responsible for most of the noise. I tried the BIOS Silent profile and a manual curve, but the fans still run around 1,600–1,800 RPM at roughly 38°C and sometimes suddenly ramp up for no obvious reason. In Windows, HWiNFO shows CPU temperatures around 53°C on average, with a minimum of 45°C and a maximum of 76°C. CPU usage is usually below 2%, although it occasionally jumps to around 9% when notifications or other background tasks run. I have mostly been browsing and haven't played any games yet. Is this fan speed normal for these temperatures? Could the issue be caused by an incorrect BIOS setting, PWM/DC mode, fan wiring, Windows background activity, or something I did incorrectly during the build? My hardware is a Ryzen 9 7900X, a B850 Aorus Elite AX V2 WiFi 7 motherboard, and an Arctic Liquid Freezer III Pro 360.
AIO cooler fan curve fan speed Hardware loud PC fans PC cooling Ryzen 9 7900X

Answers

CopperLynx22
Check how the cooler and case fans are connected. If they are plugged into the power supply directly, the motherboard may not be able to control their speed properly. Also verify that the headers are configured for PWM rather than DC when using four-pin PWM fans. A software fan-control utility can help fine-tune the curve inside Windows.
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QuietOrbit8
Those speeds are higher than necessary if the temperatures are only around 38–53°C. Try creating a gentler fan curve that starts near 400–600 RPM and gradually increases with CPU or coolant temperature. You can lower the fans further as long as temperatures remain reasonable, then make the curve ramp up more aggressively under load.
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BrightWalrus6
Small CPU usage spikes from Windows notifications and background tasks are normal, especially with a Ryzen 9 7900X. If the fans react to every brief temperature spike, the curve may be too aggressive or the temperature response time may be too short. Increasing the ramp delay or basing the AIO fans on coolant temperature, if available, should prevent those sudden bursts.
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