0db
I'll test later tonight when it is quieter to see how noticeable the fan is on stock settings but you can turn off the FAN altogether and get a 100% Passive NUC. I've updated my review with more info.
EDIT - Updated review after pushing the little NUC for a few hours with no fans.
Ok - My sound metre does not go below 50DB so I calibrated one for the phone (for what it is worth), and according to that we had a room down to around the low 30DB, but it was unable to detect the difference with the NUC On or Off....and until this test I've never noticed how "loud" birds tweeting can be! We even had to turn off a fridge in an adjacent room as it was producing more "noise" than the NUC.
So my "real" SPL was my teenage son (you know the ones that play those high pitched sounds on the phone we oldies can not hear!).
Interestingly he could not hear the fan at all till I got him to listen to right at the back of the NUC to register the sound, then move back till he could not hear it. Once he was focused on the sound he could hear it at the default 3,000 rpm anywhere in the room (max 4m).... as long as you held your breath or there was not any other noise (like those birds that kept tweeting!). I'd say it was the equivalent of someone breathing but like a more constant exhale (so less intrusive). When I turned the fan down to 670 RPM he was unable to hear it at any range (say outside putting your ear next to the port to 30cm). Obviously with the fan off there was no noise at all though he thought that with his ear pressed to the case there may have been the odd tick (expansion?).
So my summary on the NUC 2820 sound pressure levels is:
- Default Settings: Perfectly Fine for the vast majority of users, esp in normal rooms with any ambient noise. In such environments I'd rate it is inaudible at normal seating distances.
- Tweak to lower (or no) RMP: Ideal for those sensitive to any noise in very quiet rooms. The NUC will happily run at minimum RPM with 100% load but I found with this load and the fan off, it would trip the thermal trap and throttle the CPU after an hour or so (heat soak).
To me it is an intriguing unit as it is:
- Cheap
- Small
- Good connectivity
- Powerful enough to Run a full blown MC instance for all audio and video (RO Std) playback
- Low power draw
- Quiet at stock fan speeds and inaudible if you tweak the speeds.
You could get the more powerful i3/i5 NUC and the fancy (but beautiful) passive Aluminium Case from Tranquil but it is then triple the cost, though value is in the eye (or ear) of the beholder.
I've updated my review on this.
Hope it helps.