I got a NUC7i5BNH a couple of months ago, replacing my four year old NUC5i3RYH. One of the points I like about the NUCs is the noise levels, since I want my pcs to be really quiet. What I did with both NUCs is setting up the fan minimum duty cycle to 25-31% (with relevant changes to the other fields to make sure they don't overheat), which makes for a barely audible pc running at acceptable temperatures.
It seems the situation was the same for the new 7i5 model at first, but I noticed that soon the noise profile changed. While still not really loud, it gives a high pitched sound which is annoying and more audible. I'm almost certain this changed gradually, first after running intensive tasks requiring higher rpm, and afterwards all of the time, regardless of rpm.
I attach two short recordings, taken at 10cm from the NUC, one at the default 45% duty cycle and another at 25%, mostly to illustrate the noise profile.
Is this type of fan noise normal? If no, could it be due to a faulty fan?
It's technically a blower, not a fan.
What this first recording sounds like - this ticking - is likely the blades of the blower touching (rubbing) the blower's cowling. You can sometimes remedy this by tugging up on the cowling all the way around the inlet (opening) into the blower. I used a dental pick to do this the time that I had to do so (in this case, I actually caused the problem by leaning on the blower; this was while testing a bare board (no chassis)).
The second recording sounds similar, but was recorded when the blower was spinning at a faster speed (i.e higher duty cycle). That extra high-pitch "ring" could be the result of the rubbing or it could be the result of a loose bearing.
I suggest that you try my remedy. If this doesn't fix it, you can look for a replacement blower. If you cannot find one (which shouldn't be the case; it is a standard part; just use the part number on the side of it), you can always consider having Intel replace the unit under warranty...
Hope this helps,
Thanks for your reply, it's good to have such a specific explanation. I was suspecting it was a mechanical issue, but I couldn't be 100% certain due to this being a new machine and different from my old NUC. I'll try your suggestion and I'll report back.
Edit: On second thought I think I'll look for a replacement fan, perhaps if I can get Intel to send one. I can easily replace a fan, but messing with mechanical parts might be risky, not to mention that it should void the warranty and that the said blower is probably defective anyway.
Update: Rather than going through the warranty process, which would leave me without my main computer for 2 weeks at best, I order a replacement blower. This NUC comes with an AVC BAAA0508R5H 5V/0.5A blower; I received a very similar blower (I think it's AVC BAPA0508R5H) which was obviously of superior quality, as most of its parts are metallic in contrast to the plastic design of the original blower. And, other than fixing the noise issue, the replacement fan did a huge difference concerning cpu temperatures, which dropped by some 5-10 degrees. For instance, a 25% cycle duty keeps the cpu temperature in the low 40s under casual usage, and there's never any need for more than 25% unless the GPU kicks in.
Point is, it was a bit disappointing to see that Intel cut productions costs by choosing an inferior blower when there were better options. I hope they changed this in the 8th generation NUCs.