12 Replies Latest reply on Feb 7, 2016 12:27 AM by ArminM

    Processor Power calculation

    AGXIN.XAVIER

      hi

             any one has done power calculation i have selected a processor Intel Xeon E5-2430 fro a server card design

      the TDP of the processor is 80w this is only use for the heat sink design how to calculate the total power that the processor will consume when all the cores are actively performing some file streaming application or video recording and encoding the data and saving in the sata drive what is the entire power that cpu will alone consume how to calculate is there any application notes or tools from intel for calculating the power consumption

      or shall we compute from the data sheet provided values  like this is it correct ?

         

      ITTITT-TERMINATION1.0432020.86
      VSAISA-SYATEM AGENT0.9971918.943
      VCCPLLICC-PLL1.78523.57
      VCCDICCD MEMORY CONTROLLER1.5710.5
      VCCICC1350.48164.935
                           118.808

      the processor consume 120 watts of power in this 80 watts is dissipated as heat

        • 1. Re: Processor Power calculation
          Amy_Intel

          Hello, AGXIN.XAVIER:

           

          That type of information is not available from our end. However, this tool Intel® Power Gadget | Intel® Developer Zone could help to monitor the power consumption of your processor.

           

          Regards,

          • 2. Re: Processor Power calculation
            AGXIN.XAVIER

            dear sir

                         Thanks for your reply , but if a organization is designing motherboard with Intel how they will choose the power supply requirement in case of customized boards if i know the consumption in each voltage i can choose a power supply that can supply more than that ,The power gadget tool seems to be providing tdp values rather than power consumption these tools will be helpful after design but in preliminary no one will have the board in this case how to calculate the power consumption that the processor is going to consume so that i need a converter that supply more than the consumption value or if i am selecting an smps that will be capable of handling the power equal to the value of consumption +power converter loss + smps loss+offset (tolerance)+Peripheral devices power   

            or no such calculation is needed i can choose TDP limit is the max consumption ?

            but as of my understanding TDP is useful for thermal modeling how mach max heat the processor is going to provide when throttled  but for electrically calculating the power consumption how it can be done ? some thing like Mhz /uwatt with MIPS/Mhz  will be useful is this information available for the intel processors

            • 3. Re: Processor Power calculation
              Amy_Intel

              I understand your inquiry but from our end the only information in regard to power consumption is found in each processor data sheet and through the Intel® Power Gadget.

               

              Regards,

              • 4. Re: Processor Power calculation
                langtu

                CPU power is calculated as P=V^2*C*f.  Power supply will not solve your problem, because CPU get power from VR (Voltage regulator).  OEM motherboard always has specs to support CPU power.

                For example, motherboard support Xeon E5-2400 series up to 135W, your CPU rating is 80W then VR has abundant power to supply your CPU.  In case if you want to beef up power supply when you use additional add on card which requires a lot of power such as graphic card.

                 

                TDP is max power of CPU, it can allow tolerance above TDP for short period  (10% more maybe), the power control unit will scale frequency down to meet TDP power.

                 

                CPU power dissipation - Wikipedia, the free encyclopedia

                • 5. Re: Processor Power calculation
                  AGXIN.XAVIER

                  dear sir

                                Thank you for your valuable answer,actually i want to understand in depth, I have few more doubts in arriving this number 134 watt P=V^2*C*F V-Is the core voltage or which voltage we have to use In the processor we have these much rails and the value of C which capacitance switching gate capacitance is not mentioned in the data sheet  F-2.5 to 3.0 Ghz .Please elaborate I am new to intel processor based design But In the data sheet it is mentioned that the Pmax value is 145 watt for a 95 wTDP and 8-core E-2430 processor

                   

                  VCC      1.156 max

                  VCCPLL   1.785 max

                  VCCD  1.5 max

                  VTTA   0.75 max

                  VSA  0.997 max

                   

                  If we are considering vcc-core 1.2 and f=2.5  Ghz Then with a power max of 145 watt we are getting around 40 nF  How this capacitance value will be  provided  it in the data sheet ?

                  i mean gate capacitance or it depends on the nm process

                   

                  power consumption P by a chip is given by the equation P = C × V 2 × F, where C is the capacitance being switched per clock cycle (proportional to the number of transistors whose inputs change), V is voltage, and F is the processor frequency from wiki


                  C is the capacitance being switched per clock cycle -how to get this parameter? please assist me

                  • 6. Re: Processor Power calculation
                    AGXIN.XAVIER

                    hi sir

                               and we have found only the dynamic part of power consumption static part and leakage part also how to get please help me 

                    • 7. Re: Processor Power calculation
                      ArminM

                      In modern CPUs FETs are used.

                      They dissipate power only when FETs do switch - two points in every clock cycle.

                       

                      The I/O power is negligible.

                       

                      You can measure the power consumtion by measuring the current flowing into the CPU.

                      • 8. Re: Processor Power calculation
                        langtu

                        New modern CPU, the voltage is much lower such as 850mV for 2.5GHz (E5-2600 V3 series).  Capacitance is very dynamic based on feature sets such as AVX2 take a lot of power, it can range from 3 -6 nF per core, the Ring can have higher range about 18-30nF.  IO power might consume about <10% total power. 

                        Capacitance is based on nm process, it also varies within process too.  The rule of VR to support TDP has max power = 2x TDP to give CPU enough time for switching by power control unit. 

                         

                        Do you have specific processor?

                        • 9. Re: Processor Power calculation
                          AGXIN.XAVIER

                          dear sir

                                      Thank you so much for your reply i have selected Intel xeon E5 -2430 V2 1356 PIN LGA Package with 8-core i am using all the i/os that the processor can support in this case for a design report how can i calculate the processor power and we are planning to use C604 chipset how to calculate for this ?

                          link for processor

                          Intel® Xeon® Processor E5-2430 v2 (15M Cache, 2.50 GHz) Specifications

                          • 10. Re: Processor Power calculation
                            ArminM

                            What do you mean with processor power?

                            Power consumption or what?

                            You can calculate the power consumption like follows:

                            TDP+10%=~88W.

                             

                            So:90W

                            • 11. Re: Processor Power calculation
                              langtu

                              TDP is TDP, if TDP is 80W, then main components in CPU such as Core/Cache consume about 70W, the remaining for other devices such as IIO and memory controller inside the chip.  DDR has its own VR for it

                              • 12. Re: Processor Power calculation
                                ArminM

                                Then search a bit in the internet and you find websites - especially those from power supply manufacturers - how offer power consumption calculators.