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 does not quite manage the specified data, even after the 24-hour run-in. Of course, there is usually a smaller series spread involved, so let’s not be like that.
In today’s DC test, we see that the fan only starts up with voltages from about 4.5 volts, while the fan from be quiet! requires at least 3.2 volts. The cut-off voltage is 4.4 volts, whereby the technically possible 250 rpm is a long way off. This means that the fan is not suitable for real DC control, because you cannot regulate it down far enough.
The PWM-controlled startup speed is 251 rpm (with a boost of 660 rpm), so there is a fan stop and in the opposite case, the fan still spins to 249 rpm before stopping. This is ok, but not really top.
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 needs a very high starting speed of around 900 rpm, and a standstill is already below 637 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 quite high, especially at low speeds. Keep in mind that even at full load, 3 fans (without RGB) together would consume around 10 watts. 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.
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