Người hâm mộ máy tính có luôn chạy ở mức 100% trừ khi được nói không?

What happens if I do not plug it into the motherboard and it does not have a switch?

I have seen fans before with an “off/low/high” switch that allows you to manually set their speed.

I have seen fans that plug into the motherboard and are controlled by the OS.

I am curious… what does a fan do by default when plugged into a PSU? Does it run at 100% unless otherwise told to go slower? This is what I would expect…

Well, kind of. Fan speed control is done by varying voltage or through Pulse Width Modulation (using a constant voltage and cutting it up into pulses to vary speed). If you’re plugged into a motherboard, that’s what it does. If it has 3 wires, the third wire tells the motherboard what’s the speed the fan is running as. If you have a 4th wire, fan speed control is done via PWM rather than voltage control.

You can plug in a 2 wire fan to a 3 or 4 wire connector (though you lose speed feed back), and a 3 wire to a 4 wire connector (where you lose PWM control). You can also use a fan controller to control speeds.

Else, assuming the power source is unaware it’s a fan (as it would be connected through molex for example), and is at a fixed voltage, yes, it goes at full speed all the time.

Like the other guys said, pretty much yes, but I can think of 3 exceptions:

1. A few fans have a built in thermistor that will adjust speed depending on temperature.

2. PSU’s with specially marked Fan-Only PSU connectors (Antec TruePower 550W) can adjust the speed of the fan: