DeepCool FK120 fan: Efficiency ceiling for some scenarios

Initial warm-up and speed recording

It is made in the same injection mould as the FC120, but still has noticeably better properties. Stronger material, higher weight, different bearings and a more powerful motor make the FK120 one of the most attractive options among inexpensive fans. But that’s only assuming the “right” adjustment. Outside of that, this fan can be quite uncomfortable and ironically for the same reason it is sometimes unbeatable.

Initial warm-up…

Before we even start measuring anything, we let the fans run “idle” for a few minutes after plugging them in. This is because immediately after a cold start the fans reach different parameters than after a certain amount of short-term operation.

Until the operating temperature of the lubricant is stabilized, a typically lower maximum performance is achieved. This is because at lower temperatures the lubricant is denser, which is associated with higher friction. Therefore, the fans do not reach maximum speed immediately, but only after the first few seconds. Before the first measurements, we therefore leave the fans running for at least 300 seconds at 12 V, or 100 % PWM intensity.

…and speed recording

The speed of the fans is monitored using a laser tachometer, which reads the number of revolutions from a reflective sticker on the rotor. For this purpose, we use the UNI-T UT372 device, which also allows real-time averaging of samples. Thus, we do not record the peak value in the graphs, but the average speed value from a 30-second time period.

However, the speed itself is a relatively unimportant parameter that is often given more attention than is appropriate. This is the case even in many fan or cooler tests, where speed is used to normalize the different modes in which other variables are measured.

We monitor the speed of the fans with a laser tachometer

However, hyper-focusing on a specific speed is a rather unfortunate decision if only because the fans don’t gain any commonality. At the same speed all other variables are different, there is no intersection. It can be noted that a better normalization would have been by any other variable, whether it be static pressure, flow or noise level, which wins in our case. But more on that in the next chapter.

We only measure the speed so that you can associate a particular parameter (such as the amount of static pressure or some noise level) with something according to which you can adjust the fan yourself. Perhaps for that alone, the information about the achieved speed is useful. As part of the fan analysis, we will also indicate what the fans’ starting and minimum speeds are. Start-up speeds tend to be higher than minimum speeds because more force is required to get the rotor moving than once the fan rotor is spinning, and a minimum power intensity is sought at which the fan does not stall.


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Comments (4) Add comment

  1. Hello
    Your expert explanation helped me make my final choice between the two DeepCool FK120 fans and the ASUS ROG Strix fan XF120.
    The price difference of these two fans in Iran is insignificant and is around 5 dollars.
    Overall, according to your tests, I would choose the Deep Cool fan.
    I hope it is the right choice.

    Your friend from Iran

    1. Choosing the most suitable fan for a specific scenario is highly complex. In addition to the fact that all situations in practice are more or less different, each has a different set of priorities of individual characteristics. Someone may prefer lower vibrations to a slightly higher airflow, so that the fan does not end up being a source of excessive secondary noise in interaction with, for example, the case.

      But when you have looked through our tests, taken a look at the context, evaluated the pros and cons, you must have made the right decision. 🙂

      1. it would be more complex if we had more high quality fans on the market, but nowadays it’s mostly limited to whether you want maximum performance without noise or maximum performance disregarding the noise
        in the first case you get A12x25 (or T30 if you have space for that), in the other probably some monster from Delta

        if we had high quality fans optimized for specific usecases (like Noctua had in older generations, before releasing the overwhelmingly good A12x25) we could extend that choice to low vs high impedance, but nowadays S12A is entirely irrelevant and their static pressure fans are only used to save money

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