Power Consumption and Thermal Performance

The power consumption at the wall was measured with a 1080p display being driven through the HDMI port. In the graphs below, we compare the idle and load power of the Intel NUC5i5RYK (Enthusiast) with other low power PCs evaluated before. For load power consumption, we ran Furmark 1.12.0 and Prime95 v27.9 together. The numbers are not beyond the realm of reason for the combination of hardware components in the machine.

Idle Power Consumption

Load Power Consumption (Prime95 + FurMark)

By default, the BIOS puts the unit in the maximum power consumption / performance mode. The above numbers are with those default settings. It is possible for the end-user to drive down the numbers further with tweaks in the BIOS (at the cost of performance)

In terms of thermal design, the NUC5i5RYK is no different from the Haswell NUC. There are ventilation slots on the side and a small fan directly beneath the lid helps draw in air over the heatsink that is placed behind the slots. On the other side, the lid has a thermal protection strip adhered to it such that it gets placed directly over the M.2 SSD. This ensures proper cooling for the storage media (an issue that one of the previous generation NUCs faced). In order to evaluate the thermal performance, we started with the system at idle, followed by 30 minutes of pure CPU loading. This was followed by another 30 minutes of both CPU and GPU being loaded simultaneously. After this, the CPU load was removed, allowing the GPU to be loaded alone for another 30 minutes.

In the pure CPU loading scenario, the cpre frequencies stay well above the suggested base value of 1.6 GHz, thanks to the BIOS setting controlling the maximum allowed sustained power consumption. The turbo burst frequency of 2.7 GHz is observed only very briefly, and the cores settle down to between 2.4 and 2.5 GHz. We see the temperature stabilizing slightly above 80 C (despite the junction temperature being 105 C). On the other hand, when the CPU and GPU are both loaded, the frequencies drop down to around 1.3 GHz for the cores. The GPU is advertised to run at a base clock of 300 MHz, with a turbo mode of 950 MHz. The actual frequency stays above 700 MHz comfortably throughout our stress test. In the absence of any CPU load, the cores drop down to 800 MHz. The temperatures are also below 80 C throughout the time that the GPU is loaded up. The behavior of the clocks is similar to what we observed for the GIGABYTE Broadwell BRIX s.

The above graph presents the power consumption at the wall during the above thermal stress run. This shows that Intel has designed the NUC with a certain maximum power budget in mind, and the clocks of the CPU and GPU are adjusted depending on the load to obey that configurable TDP. One interesting aspect is that the GPU clock at idle is always reported to be 900 MHz by various tools. We assume there is some sort of inner clock-gating going on beyond the observation point. Otherwise, it is possible to drive down the idle power consumption even further. The thermal performance of the enthusiast build was along the same lines, with a cap of around 34 W for the maximum power consumption at the wall.

All in all, the thermal solution is very effective. Given that the acoustic side-effects were not irksome (subjectively) and the temperature of the CPU package was well under the junction temperature limits, we wonder if Intel has missed a trick by dialing down the overclocking and not allowing the full performance potential of the system to come through with the default BIOS settings.

HTPC Credentials Final Words
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  • seanleeforever - Monday, February 23, 2015 - link

    true, i suppose if your requirement is to play 4K UHD video no matter what encoding used, then you really have to step up to a faster processor. Reply
  • duploxxx - Monday, February 23, 2015 - link

    fixed with carrizo which will launch pritty soon. Reply
  • StevoLincolnite - Friday, February 20, 2015 - link

    I must be the only person who is still using an Atom 330 from god-knows-how-many-years-ago.
    It's slow and it sucks.

    But with a Broadcom Crystal HD, it does *everything* I have asked of it, which is maintain my library and playback movies.
    One day I will upgrade... full-fledged Windows Tablets have now hit the $100 price point, you would think I could get a full blown Atom powered HTPC for half that, right? As it doesn't include a screen? Hahaha. Wrong.
    Reply
  • kmmatney - Friday, February 20, 2015 - link

    Yeah - I just bought a Winbook 10" tablet for $149 at Microcenter. Specs: 10" IPS screen, 32GB "SSD", 2GM RAM, Win 8.1., USB and mini HDMI port. Runs movies great, and great for internet browsing, runs my programming environment, and can even run Minecraft (with optifine). I have both an Android tablet (with high density display) and an iPad4, and I can't really say the display on the Winbook as any worse - pixel size is fine. I ended up selling my Android tablet, and would sell my iPad if the rest of the family would let me. This $149 tablet blows them both away. It could easily be an HTPC with a blue tooth keyboard and mouse. It's doesn't compare to a Core i5 in speed, but it's fast enough. Reply
  • Antronman - Friday, February 20, 2015 - link

    A $728 dollar build is easily going to fit the A10-7850k

    The only advantage the NUC poses is power draw and operation volume.
    Reply
  • Gadgety - Friday, February 20, 2015 - link

    For an HTPC which also would be used for light gaming, then I believe an AMD A8-7600 or the Carrizo version, in a passively cooled case is better than these Intel offerings. Mainly from a cost and size standpoint, as the Intel system would need a graphics card. For just movie/TV kind of usage then I believe the Intel offering handles the 23.976 better than AMD. Reply
  • yankeeDDL - Friday, February 20, 2015 - link

    Carrizo will have full H.265 support in hardware. Usually that makes just the world of difference in terms of efficiency. Reply
  • BlueBlazer - Saturday, February 21, 2015 - link

    But for Carrizo, does not mention support for VP9 (used by Google TV) or 10-bit H.265. Reply
  • Teknobug - Friday, February 20, 2015 - link

    In my experience, yes and no, enough power to play videos but hardly enough umph to do anything else. I tested an A4 5000, A6 1450, A8 5545M, A10 5750M and A10 7300, the A10's run hot but has a good enough GPU for low-mid range gaming and the lower end AMD's get beat out by Celeron N28** and Pentium N3530 and even the A8 gets beat out by i3's. Reply
  • Samus - Friday, February 20, 2015 - link

    The only downside of AMD htpc's is obviously higher power consumption. It will simply need more cooling. That may be negligible to you if a near silent fan in a quality case with proper ventilation is part of your build.

    I personally use a passive cooled shuttle j1900-based htpc. It has no moving parts, not even a fan. That was important to me because my TV room is dead silent... and I paid dearly for a clean amp to have no speaker hiss so having no fan noise is priceless.

    People with a projector or less demanding requirements should save their money and just build an inexpensive AMD htpc.
    Reply

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