How can I stop my 7800X3D fan ramping up during light tasks?

Try the fan curve first. Short CPU temperature spikes can make a fan chase every little change, even when the load disappears a moment later.

In your motherboard fan controls, look for a response delay or hysteresis setting and try around five seconds if available. You can also make the lower part of the curve less steep. Keep enough cooling for sustained loads, then check temperatures under a longer workload to make sure the fan still ramps up when needed.

You can use separate Windows power plans if you don't mind switching. In advanced power settings, try setting Maximum processor state to 99% in a quiet plan. That can disable boost and reduce the spikes, but it also costs performance while that plan is active.

Keep another plan at 100% for gaming or other demanding work. A desktop shortcut to powercfg.cpl opens Power Options quickly, so switching doesn't take much digging.

Check the cooling setup too, especially if temperatures stay high under load rather than just spiking briefly. Make sure the cooler is mounted properly, the protective film was removed, and the fans are working. A brief spike alone doesn't tell you whether the cooler is faulty.

Curve Optimizer is another option if you're comfortable tuning the BIOS, but I wouldn't start with a large negative value just to fix fan noise. Any setting needs stability testing, and a smaller negative value may be necessary if the system becomes unstable.