Start-up and shut-down voltage
This chapter should be read with caution and attention as long as the fans are not purely analog, i.e. DC-controlled with 3-pin connector. The PWM control electronics almost always stand in the way of clean voltage regulation and it is also therefore not advisable to regulate PWM fans via voltage. Nevertheless, we also performed this measurement for all models, regardless of whether they are DC or PWM fans, because even strange results say a lot about the control electronics and the use as a DC-controlled fan.
First, however, we check the maximum speed at 100% PWM to be on the safe side and compare it with the data sheet. The fan achieves the specified data and is even slightly above it after the 24-hour run-in. Of course, there is usually also a smaller series dispersion in play, so that already fits.
In today’s DC test, we see that the fan only starts up with voltages from about 3.5 volts, while the fan from be quiet! requires at least 3.2 volts. The cut-off voltage is 3.2 volts, whereby the technically possible around 300 rpm is far away with the measured 900 rpm. This means that the fan is not suitable for true DC control, because you cannot regulate it down far enough.
The PWM-controlled startup speed is around 290 rpm (with a boost of almost 900 rpm), so there is a fan stop and in the opposite case the fan still spins up to 298 rpm before it stops. This is certainly strange at first glance (because this is normally below the startup speed), but the PWM controller chokes when regulating down in all speed ranges (larger fluctuations).
Start-up and shut-down behavior
The following measurement curves once again illustrate the very different behavior. Let’s look at DC control first. The new fan requires a very high starting speed of around 900 rpm, and a standstill already occurs below 750 rpm. That is nothing.
With the PWM protocol, we can also see very well the progression up to the minimum speed, which then leads to the desired standstill.
Power consumption
This value is pleasantly low, especially at low speeds. However, you should also keep in mind that 3 fans (without RGB) would consume around 10 watts together at full load. From this point of view, a common DC control of all installed fans of a system via a single 1-A header would be rather impossible if there are more than three. So rather PWM and via hub with SATA supply.
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