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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  • owan - Friday, February 20, 2015 - link

    I wouldn't. The GPU on the low end APU's isn't *that* much better than intel's IGP and the TDP's are too high, which is a big consideration IMO for a device that may spend quite a lot of its time running. I've found my Celeron G1820 system to be superior in every way than the A4 system it replaced, except in casual gaming where they both were basically useless. The CPU gap can absolutely be relevant when you start messing with different decoders as well. Reply
  • yankeeDDL - Friday, February 20, 2015 - link

    The laptop is a Lenovo Z50, with Kaveri's A10-7300. With default settings, I haven't found a game which is not playable yet. And it costed me nearly half the NUC in this article ($400).
    Regarding which HTPC to buy, I was looking into Zotac's: something to stash behind the TV, away from view.
    I agree with you that the savings on low-end AMD APU's are not worth it: the A10 is already dirt cheap.
    Reply
  • jimjamjamie - Monday, February 23, 2015 - link

    I just recently bought the Z50-75, lovely machine for the price. 19W CPU in a 15.6" chassis is great for low fan speed and cool operation, even when it's turbo'd up at 3.2GHz. I don't rate it much for games though as it is not powerful enough to drive 1080p without dialling back the quality settings. Reply
  • cjs150 - Friday, February 20, 2015 - link

    owan et al: I have owned AMD machines before, and will probably do so again in future. The problem is TDP, they run too hot. In my main HTPC I run an i7-3770T (45w TDP). More than sufficient power for transcoding. When I built that machine, AMD had nothing even close. The problem with going fanless is heat, and AMD are way behind on this.

    HTPC use is very personal. I do not want to go 3D and 4K is currently unnecessary. But it may be that h.265 codec is too CPU intensive for what I have. If so then I will build new machines - but as that will probably be several generations of CPU in future, it is not a problem (and when it is, it will be fun to build!)
    Reply
  • yankeeDDL - Friday, February 20, 2015 - link

    To each its own. It's good to have choices :) Reply
  • seanleeforever - Friday, February 20, 2015 - link

    cjs150: try amd 5350 APU. i run it without fan, it is a 25W TDP SOC (so all the IO memory controllers on build on the processor with Radeon HD 8400 ).

    i too find this review lacking to say the least. i build ultra small factor PCs for fun, and i have yet to find one that beats AMD's offering for general windows use in a ultra tiny factor.

    the only three issues with AMD solutions is
    1. driver under linux are not that great, but it is getting better.
    2. smallest form factor is ITX, which is still too big ESPECIALLY consider 5350 is a SOC.
    3. stock cooler sucks. it has the worst oem cooler i see in my entire life.
    Reply
  • TheinsanegamerN - Saturday, February 21, 2015 - link

    hate to tell you, but the 5350 is NOT an SoC. It is just a low TDP CPU, because the memory is still external. the memory needs to be in the chip in order for it to be considered a SoC. an integrated memory controller has been standard from 7 years, that doesnt make the chip a SoC.
    And ITX isnt too big. you can build mac mini type systems in that size. anything small is proprietary, and OEM only. see the NUC above. you cant by a motherboard for that.
    Reply
  • seanleeforever - Monday, February 23, 2015 - link

    the name "SoC" means a number of things, i suppose you could say it is not SoC by your standards but many website (Anandtech, the one you are commenting on, says "...Athlon 5350, a quad core SoC"), similarly, if you define SoC as something that must have on board memory by design, then you can pretty much rule out all the snapdragon processors since they don't have on board memory. So i would like to believe your definition is flawed, as so will most people.

    secondary, you are dead wrong about it is just a low TDP CPU. go research the 5350 Spec, one thing it stands out is that not only does it have memory controller, but it also feature a video controller , TPM, PCIe lans, Sata port, VGA output, USB3 and USB2, and PS/2 all on the CPU. the thing about SoC is that it is a System on Chip (minus other stuff like storage, ram, power...etc). it has all the I/O (south bridge), and memory controller (North bridge) all build in one die. this is more similar to cell phone processor than traditional computers. this allows M/B to pretty much just bring out pinouts.

    i suggest you to know your subject before posting. this is anandtech and i do expect user to have some basic knowledge in the comment section.
    Reply
  • extide - Monday, February 23, 2015 - link

    TheinsanegamerN -- NO Processors have all the memory built in -- The most memory you can get is on Crystalwell, but thats still cache. In phones you get PoP which means Package on Package, meaning a SoC underneath and then a regular memory chip on top.

    A CPU is generally considered a SoC when it requires no north bridge or south bridge, ie it has memory controller, pcie controller, usb, sata, GPU, etc.
    Reply
  • BlueBlazer - Saturday, February 21, 2015 - link

    That AMD 5350 APU still has a weak CPU. Also its 25W thus it should not be run without fan. That's why the stock cooler has a fan. And due to that weak CPU, it has problems with higher resolution videos: http://www.guru3d.com/articles_pages/amd_athlon_53... quotes

    "We also tested Ultra HD video acceleration. Above the 4K resolution Elysium Trailer, here we have an MP4 H.264 file and you can see that the CPU load is 52% with one core topping out performance. Unfortunately Ultra HD videoplayback resulted into stuttering. For both content we have additional shaders enabled like image sharpening and darkened black levels.

    The reason why we noticed stuttering seems to be that the trailer is not DXVA encoded. meaning of you where to RAW decode video streams over the CPU, it would not be powerful enough. The GPU at DXVA will take care of you on that here though."
    Reply

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