For all the technical prowess that the Steam Deck represents, there is one annoying issue that seems to concern a few owners so far. Fan noise. But not everyone. Turns out that, according to a recent reddit thread there may be two different fans used in the commercialized version of the Steam Deck:

• The Delta fan (reference BSB0505LA-00)
• The Huaying fan (reference BN5010S5H-N00P) - apparently also used in dev kits.

It seems that the high pitch noise concerns the Delta fan only, as shown in this video:

Someone on Twitter went ahead and did a Fourier transform of the video sound to show how the frequencies of the fan noise differed:

There is indeed a very noticeable noise peak between 3.5 and 4 Mhz. One of the hypotheses is that the fan is using a completely symmetrical design, as shown by the following Xray, and that it is more likely to cause such sounds when rotating:

You can see that on the OLED Nintendo Switch they went for a different fan design, with asymetrical blade spacing, that helps to change the profile of the noise.

Now, it appears that the other fan, the Huaying one, makes less noise in the Steam Decks, while still appearing to be symmetrical in design as well. So, that may not be the only factor explaining the specific high pitch noise. It could also be that the enclosure of the Huaying fan is a little different from the Delta one, and the enclosure can also help mitigating the resulting fan noise.

In any case, this is an insightful observation, and while there may be a software solution for it (Valve could adjust the fan speed profile to reduce the noise impact), there could also be a solution to replace one’s Steam Deck’s fan with a less noisy alternative, if it can be secured from channels such as iFixit.