3 Replies Latest reply on Jun 10, 2016 1:16 PM by Intel Corporation

    High Idle power consumption and TDP Limit

    YounesGhanem

      Hello Everybody,

       

      In Idle mode (CPU utilization <1%), my NUC6i7 is consuming about 19W average.

      No matter how I set the TDP in the BIOS. Do you also have that  ? I find this particularly high.

      Anybody knows if it's normal ?  As an example, a NUC5i7 consumes about 7W.

       

      This happens even if I set the "power options" settings (Win 10) to "power saver".

       

      Other point where I'd like to have your opinon :

      For an application, I need to limit the TDP of my NUC6i7 (to avoid heating and high power consumption).

      For example, I've got following configurations that's working  :

       

      VR current limits : 40A

      Package limits (sustained) : 15W

      Package limits (Burst) : 25

      Tau (window) : 14s.

       

      These features are under-dimensioned for the NUC6i7. How can I make sure that this is stable ?

      I let run a "torture test" with Prime 95 two days long and it seems to be sufficient for me.

       

      Thank you for sharing,

       

      Regards

       

      Aa.

        • 1. Re: High Idle power consumption and TDP Limit
          Lokutos

          YounesGhanem wrote:

           

          In Idle mode (CPU utilization <1%), my NUC6i7 is consuming about 19W average.

          No matter how I set the TDP in the BIOS. Do you also have that ? I find this particularly high.

           

          Yes, this seems to be normal. I guess you measured at the outlet. I'm seeing about 19W consumption there in idle. This NUC uses a 120W PSU. PSUs often are less efficient on the extreme ends (low or high load), so of those 19W maybe only 12W or so reach the NUC. There you have additional losses in the VRs etc. The package itself only consumes 3-4W or so in idle (according to the CPUs own estimation). That's why changing TDP in the BIOS doesn't change a thing. The power is spent elsewhere. Add about 1W for idle DRAM. Also on this NUC the PCH is not part of the CPU package (AFAIK) and also consumes power.

          Your comparison with other NUCs (such as the 5i7) isn't that valid because those NUCs use a 60W PSU (which probably means better efficiency at the same low power point) and have an integrated PCH.

           

          Other point where I'd like to have your opinon :

          For an application, I need to limit the TDP of my NUC6i7 (to avoid heating and high power consumption).

          For example, I've got following configurations that's working :

           

          VR current limits : 40A

          Package limits (sustained) : 15W

          Package limits (Burst) : 25

          Tau (window) : 14s.

           

          These features are under-dimensioned for the NUC6i7. How can I make sure that this is stable ?

          I let run a "torture test" with Prime 95 two days long and it seems to be sufficient for me.

           

          For your TDP changes: I wouldn't change the current limit. It's enough to change the PLs. No need to test stability. You configured the package down. It cannot become unstable because of that. It will just throttle clocks to try to maintain the limits. Because of cooling system inertia, I think you could get away with a higher burst limit (PL2), improving performance for spiky work loads.

          • 2. Re: High Idle power consumption and TDP Limit
            aaroni

            Hi,

             

             

            Thank you for the answer.

            I think the PSU doesn't play a big role here : I used several different labor power supply and I still get 19W.

             

            That with the integrated PCH sounds interesting :I'll spend some time with that.

             

            Thanks a billion

             

            Cheers

            • 3. Re: High Idle power consumption and TDP Limit
              Intel Corporation
              This message was posted by Intel Corporation on behalf of

              Hi YounesGhanem,
               
              The power consumption of the NUC is variable; it depends of all the hardware installed on the kit. Now, the processor of the 6i7KYK requires almost the double of the power of the 5i7RYH, it has a quad Core processor with better graphics performance.
               
              Comparison chart:
              http://ark.intel.com/compare/84993,93341
               
              Regards,
              Mike C