Kaby Lake i5 NUC Review 3/3: Fan, Power, Conlusions (NUC7i5BNK)


Fan Noise

The Kaby Lake i7 was slightly disappointing when it came to the noise levels so my hopes were high when it came to the i5 model. With the BIOS set to the default settings the fan does spin up quite easily, even when doing basic tasks like web browsing. Under full stress the noise levels do increase to a relatively noisy levels, however, it’s not nearly as bad as the i7 model was. Simultaneous stress of the CPU and the GPU pushed the i7 model up to 44 dB, whereas the maximum I measured on the i5 was about 40 dB. I’d say it’s even not so much about the level of the noise, but it’s more the profile of the noise that makes it more annoying. I’d say my i5 laptop is equally loud, but the noise profile is much more pleasant.

That being said, setting the fan profile to “Quiet” did make the NUC almost completely silent for web browsing and basic tasks like that. However, under full stress the results are obviously the same as the fan just needs to spin up to a certain level to keep the CPU from overheating under stress.

The following measurements are taken using a cheapo UNI-T UT353 sound meter and the BIOS of the NUC was set to the default settings. I’m pretty sure that my completely unscientific approach is quite laughable for the people who actually do this kind of thing for living. I’m also pretty sure that the numbers produced are not comparable with numbers produced by someone else in their tests. I’ve measured from the front of the NUC with the microphone of the meter 50 cm away from the front panel. I’ll try to do so with my future NUCs so hopefully the numbers can be compared between my measurements.

Task Power
Power off (noise floor) 33.5 dB
Windows 10, idle on desktop 34.8 dB
Prime95 running stress test on all cores
(CPU temperature 86 degrees C)
40.1 dB
3DMark Time Spy Demo
(CPU temperature 86 C occasionally)
37.3 dB,
but occasional peaks at 39.6 dB

It’s worth noting that 39 decibels is really quite much more than 33 decibels even if the numbers do not seem so much different. When the power of a sound source is doubled the sound level increases by 3 dB.

Power Consumption

I also took some power consumption measurements for the Kaby Lake i5 NUC.

Task Power
Windows 10, idle on desktop 13.6 W
Prime95 running stress test on all cores 48.1 W
3DMark Time Spy Demo 45.4 W
MPC-HC playing 10-bit 120Mbps HEVC at 4k 19.2W

The power consumption figures explain why the i5 model did not get as loud as the i7 did. Whereas the i7 reached up to 60 watts at some points, the i5 model stayed below 50 watts at all times. The chassis and the cooling solution for the i5 and the i7 models are very similar, so dissipating that extra 10 watts of heat obviously requires higher RPM of the fan.


The Kaby Lake i5 NUC (NUC7i5BNK or NUC7i5BNH) is a capable mini PC. When compared to the previous generation the performance has improved, albeit not that much. However, I wrote last year that pretty much the only thing that I thought was missing from the Skylake i5 NUC was a HDMI port and the capability to HW decode 10-bit HEVC video. This NUC does all that and more: there’s limited HDMI-CEC control capabilities, USB 3.1 port, external GPU connectivity via Thunderbolt 3 port and more.

The fan is a bit noisier than I had hoped. At the moment that would be the only thing that is curbing my enthusiasm over this NUC. You can modify the behaviour of the fan in the BIOS and that does improve the situation a good bit. Of course, you could move the mainboard to a completely fanless Akasa case and be done with it. They don’t come cheap though…

Other than that, this NUC strikes a great balance between performance, price and power consumption. It would be a good desktop replacement for people who don’t have great performance demands. If you’re finding it hard to understand the level of performance you can expect, it’s maybe good to compare the NUC to a laptop. A good upper-midrange laptop with an i5 CPU will feature similar performance as this NUC.

Recommended Setup

This time the recommended setup has 8 gigabytes of DDR4-2133 RAM that is known to work well in this NUC and a 275-gigabyte Crucial SSD drive. If you would like to equip your NUC in a different way or you’d prefer the NUC7i5BNH model with the 2.5″ slot, have a look at our build-a-NUC tool: the NUC Guru that will give you sound recommendations on your NUC setup.

Product US UK DE FR
Intel Kaby Lake i5 NUC NUC7i7BNK $397.00 £384.19 EUR 422,73 EUR 448,61
Kingston HyperX 2x4GB DDR4-2133 RAM (8GB) $73.79 £77.62 EUR 89,43 EUR 89,45
Crucial MX300 275GB M.2 SSD drive $99.99 £88.61 EUR 96,89 EUR 99,99
Check out the total price of the whole setup on Amazon.com!


12 Responses

  1. hans says:

    Very interesting review! And I am glad you compared the i5 and i7 version. But could you give a short comparison (especially regarding the fan noise) between the i5 and i3 7th gen NUCs? I am going to buy one of those, and currently prefer the i5 – but if the i3 is much more quite I would think about that again.

    • Olli says:

      Hi Hans, thanks for the feedback. Unfortunately I don’t have the i3 at my disposal any more so I cannot really compare them side-by-side. I think it was more quiet, but you can also adjust the fan behaviour of the i5 NUC. The fan unit in both NUCs is exactly the same, so it will be equally noisy at equal temperatures. The question I guess then is, will the i3 heat up as quickly as the i5 does?

  2. Matt says:

    Another great review, thanks.
    I’m pleasantly surprised by performance increase over the last generation i5, and also the Broadwell version of the i7. Astonishing gains in performance if you consider Broadwell was only 2 years ago.

    I think this i5 box will have a fair amount of longevity in it considering the 4k output, Thunderbolt, USB-C, good single/multi core performance. For a HTPC it’s more than enough, and even sufficient for moderate gaming. We use the Skylake i5 for games like Cities Skylines, and although the settings have to be tuned a little, it does a good job.

  3. Jacob says:

    I would also like to see the measurements on fan noise and power consumption regarding the i3 7th NUC. I am also interesting to see some gaming numbers on the i3 7th NUC, just to be able to compare it with the i5 and i7 NUCs.

    • Olli says:

      Hi Jacob, unfortunately I don’t have the i3 NUC any more. My gut feeling is that with the default BIOS settings it was more quiet than the i5, but take that with a pinch of salt. Unfortunately I don’t have anything better than the Cinebench OpenGL and the 3DMark results. These do typically correspond relatively well with games, though each game is a bit of its own… In general, I don’t think the i3 should be used for much gaming! Maybe some older games or ones that are not demanding for the GPU.

  4. Jon says:

    Great review as usual. Have you tried using this with a 4K TV as display? Over at the NUC forums there have been many threads about various display problems at 4K for this NUC model (and others).

    • Olli says:

      Hi Jon and thanks for the feedback. I don’t unfortunately own a 4k television (maybe it would be a time to get one?!) for testing this. There were a lot of issues with the Apollo Lake and Kaby Lake NUCs (and SoCs from other manufacturers, such as ASRock) when it came to 4k TVs and the HDMI 2.0 port. Most of them were resolved with the LSPCon firmware upgrade to 1.66. For example, many Samsung TVs don’t work ok with these NUCs if you don’t do the upgrade!

    • Olli says:

      There’s also this post by Intel employee: https://communities.intel.com/thread/113742

  5. nbzn says:

    Now I have to add in the cost of Akasa if I want that quiet experience with 7i5…too bad they dropped support for 7i7 from PlatoX7, that combo’s performance/price might have been a better fit for me.

    Maybe I can be patient and see what plays out in the next few months.

    Thanks for the great review Olli — much appreciated.

  6. Patrik says:

    Is it not possible to replace the fan from a third party manufacturer on the NUC´s ?
    The cost of an Akasa chassi is a bit steep.

  7. Wojtas says:

    14 W idle v. 9 W idle in previous generation? And default idle fan speed? 4k v. 3k??
    The new NUC can not be quiet…

  8. Anthon says:

    Is there any method to limit power consumption (and performace) in idle mode? By the BIOS or Windows PWM?

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