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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  • gfieldew - Saturday, February 21, 2015 - link

    Damn, wrong post, please ignore. Reply
  • medi03 - Sunday, February 22, 2015 - link

    Lack of AMD APUs in comparison charts is somewhat suspicious, to say the least. Reply
  • mits2k - Monday, February 23, 2015 - link

    I am glad that Anandtech is evaluating 4K playback on these devices. Regular 1080p HTPCs seem to have reached a plateau in the past few years.
    I was confused by the evaluation of 4K scaled to 1080p. Are the new LAV filters that fix the scaling issues incorporated into the latest MPC-HC? Will LAV be taking advantage of the partially in-hardware 4K decoding via DXVA on Intel QuickSync soon? Does the HDMI output of this device support HDMI 2.0, enabling 4K/60p/4:4:4 color bit-depth? If not, does the DisplayPort support this bitrate? Will this device support HDCP 2.2 for protected 4K bluray output?
    I bought an ASUS chromebox ($179 version) and have been successfully using it with my 4K monitor (Monoprice model) and 4K TV (Samsung). It renders the desktop in 4K30Hz, not at 60Hz. It is too slow/there is not appropriate software in linux to handle 4K videos without occasionally dropping frames, so I was going to upgrade to the NUC to handle this.
  • rangerdavid - Monday, February 23, 2015 - link

    "The first Sandy Bridge NUC was important for two main reasons - the obvious one being the kickstarting of the UCFF craze."

    What, no nod to the Mac Mini, circa 2005? (Or even the G4 Cube if you want to geek out with me...)
  • Kidster3001 - Friday, February 27, 2015 - link

    He didn't say NUC was the first but that it kick started the current popularity of the form factor. Reply
  • Haravikk - Wednesday, February 25, 2015 - link

    I'm doing quite well on a small form factor system at the moment, using an i7-4790T (45W 2.7ghz quad-core, hyper-threading, 3.9ghz turbo and HD4600 graphics) in an Akasa Euler case. Only downside has been that I had to trade in the mSATA hard drive I was using for a regular 2.5" SSD, as the mSATA just got too hot in such a confined, passively cooled space. Reply
  • jasperjones - Wednesday, February 25, 2015 - link

    I am shocked what you guys use as a HTPC. And what good are these SSDs in a HTPC???

    I use a rooted Amazon Fire TV as my HTPC (purchased for € 49 at the introductory rate for Prime customers). Thus far, it has handled everything I've thrown at it. By the time I need H.265 and 4K, I imagine another ARM box priced below a hundred bucks will be around.

    To me, this NUC is a desktop replacement (for non-gamers) or a small-server replacement.
  • nerd1 - Sunday, March 1, 2015 - link

    I have no idea why somebody is even bothering to try AMD - they are horrible.

    I am in market for small and lightweight PCs, and have used AMD once - it ate twice the current of NUC yet twice slower. So 1/4 performance per power. Oh and it wasn't that cheaper too.
  • piasabird - Tuesday, March 3, 2015 - link

    Well I would just compare this to at least a desktop Pentium, i3,i5, i7 to see what the difference is. Is this weak slow running processor as good as say an i3 4330 that runs at 3.5 Ghz, with 4 Megs of Cache, and HD 4600 IGP? Reply
  • Ceois - Wednesday, March 4, 2015 - link

    On the first picture from the BIOS gallery it says CPU Core Temp 51C. Isn't that a little too high for it being idle? Reply

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