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What do I need for PWM fans?
To use this feature, you’ll need a motherboard with a PWM header and the appropriate software (for help shopping, see our motherboard buying guide). Most mainstream motherboards have at least one 4-pin PWM header, and the best motherboards usually have to four to six. Note, older fans may use 3-pin connectors.
Can I use a PWM fan without PWM?
If no PWM signal is present, almost all fans will work on 100% of power, while most pumps used in water cooling will operate at some medium speed. Meaning, if you want to run the pump on full power, you need to hook it up to a PWM signal that is set on 100% duty cycle.
Are PWM fans always 4-pin?
PWM fans come with a 4-pin connectors for fully automatic speed control via your mainboard’s 4-pin PWM fan headers. When connected to 3-pin fan headers, the fan will run at full speed (unless the mainboard supports voltage based speed control).
Do you really need PWM fans?
Unless you are going for some very high overclocks, but even then the stock fans are enough to provide the airflow your case needs. As long as you have that good basic airflow (which can be achieved with a combination of pretty much any fans) it all depends on your CPU cooler.
Should I use PWM or DC?
The main reason that PWM fans are better than DC fans is that they will spin at lower speeds. So if you can get enough airflow at these low RPM’s then it’s advantageous to have PWM fans.
Is PWM better than 3 pin?
The future is definitely for a 4-pin connector on the motherboard header around the VRM section. As you know these PWM fan connectors are much the finest compared to 3 pin fans. Also, 4 pin coolers are most often used to cool the processor, while conventional fan coolers can have 3 pin connectors.
Are PWM fans noisy?
As previously explained, PWM acoustic noise is caused by the impulse torque generated by the fan motor during each active PWM cycle. Reducing this acoustic noise involves slowing the slew rate of the PWM switching, thereby “smoothing” the PWM impulse torque profile.
Why are PWM fans better?
The speed of regular fans can be modified by voltage regulation. PWM on the other hand lets it rotate faster or slower, depending on the situation. If they are rare then the fan will rotate slowly, and if they are frequent then it will spin fast.
How big of a resistor do I need to reduce fan speed?
To reduce the voltage by 1.3 volts would require 0.65 ohms. The power in the resistor would be 2.6 W, but it is not a good idea to run the resistor at its rated power, so use 5 watts. Since this is all estimated, you might look for a 1 or 2 ohm 10 watt variable resistor.
How is the PWM used to slow down a fan?
The fan takes a 3.3v inverted PWM in, so a constant 0v or 3.3v FG signal will fail safe, with the fans running at 100%, while increased duty cycle on the PWM will slow down the fan.
What should be the current of a 5.2ω fan?
At full speed with a 5.2Ω fan, a 3.7Ω resistor in series should, according to my naive assumptions, drop the overall current to 1.35A (16.1W rather than 28W) with 6.75W through / 4.7V across the resistor and 9.45W through / 7.0V across the fan. That’s 34% of the original power to the fan.
When does the resistance of a fan go up?
If the fan is driven at less than 100% PWM, it’s effective resistance will go up as the current draw goes down. Re-running the above calculations, I get: