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 a 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 easily manages the specified data and even slightly exceeds it after the 24-hour run-in. Of course, there is usually also a smaller series dispersion in play, so that already fits, even with the unlit fan.
In today’s DC test, we see that the ARGB fan only starts up with voltages from about 3.7 volts. The cutoff voltage is 3.2 volts, whereby the technically specified 800 rpm slightly differs from the measured 934 rpm. And it also doesn’t start up again until 953 rpm. Thus, the fan is not suitable for real DC control because you cannot regulate it down far enough.
The PWM-controlled start-up speed is plenty 840 rpm (no extra start pulse), so there is a fan stop, because fans stop underneath at some point.
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 starting speed of well over 900 rpm, and there is also a standstill underneath. As a control range, this is worse than PWM control and makes these fans almost useless as DC-only fans (see above).
With the PWM protocol, we can also see very well the progression up to the speed, which then leads to the physically conditioned standstill and the switch-on pulses to safe starts…
Power consumption
This value of open operation as a case fan is pleasantly low, especially at low speeds. However, you should also consider that at full load, four fans would consume around 8 watts together (even up to almost 12 watts at peak), which a single 12V DC header can just about supply. 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 impractical to impossible and also rather pointless due to the narrower control ranges. Then rather PWM, which regulates better.
However, power consumption is not the same as power consumption, because it fluctuates quite a bit between radiator operation and free installation as case fan! This graph is also new and should help in assessing the system load, as the power consumption increases to a maximum of 2.8 watts on the radiators. And that too only in the peaks, but you have to include it.
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