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So if TDP is a measure, given in wattage, of thermal dissipation of a CPU under a typical load. Why can't I simply assume double that value for a CPU's actual p

So if TDP is a measure, given in wattage, of thermal dissipation of a CPU under a typical load. Why can't I simply assume double that value for a CPU's actual power consumption under heavy load? I mean, using that logic the max power consumption for the same six core processor Atwood tested would be around 280 watts. A number only 40 watts higher than his for heavy load. Too bad I used "false information" to reach such a usable number. Now if the actual power consumption was double that, I'd definitely be berating Intel. But alas, no.

ksk 10y ago
Practically, sure, you pretty much have to do whatever it takes to get it working. But its not like we're talking about trade secrets here. They simply have to release a coherent definition of what they consider a typical load. I get your point, but nothing wrong in drawing attention to the specs being incomplete to the point of being useless.
- msimpson 10y ago
  > They simply have to release a coherent definition of what they consider a typical load. Have fun getting AMD and Intel to agree on something. > I get your point, but nothing wrong in drawing attention to the specs being incomplete to the point of being useless. Vague or averaged is not useless.
  - ksk 10y ago
    What does Intel documenting their own specs have to do with AMD?
    - msimpson 10y ago
      TDP is used by multiple manufacturers, so getting a "coherent definition" is going to take work. If you want to understand more about the thermal specs from only Intel. You can read their thermal guide: http://www.intel.com/content/dam/www/public/us/en/documents/guides/xeon-e5-v3-thermal-guide.pdf http://www.intel.com/content/dam/www/public/us/en/documents/...
      - ksk 10y ago
        Sorry, I don't understand your point. Each vendor already defines it in their own way. The point of the article is that without proper guidance you end up guessing. I'm afraid the guide you linked to doesn't help much. Intel confusingly tells us "TDP: Thermal solution should be designed to dissipate this target power level. TDP is not the maximum power that the processor can dissipate." So according to Intel [1] - "The best way to measure a server’s power consumption is the power meter, an inexpensive tool that is plugged into the wall, and then your device, like a server, can be plugged into the power meter. The meter displays the wattage drawn "at the wall" and allows you to analyze the power consumption under a variety of different utilization levels.". Strange. I was looking up docs on AMD. They seem[2] to kinda get it: "To allow optimal reliability of the AMD Opteron and AMD Athlon 64 processor-based systems, the thermal and cooling solution should dissipate heat from a processor operating at its maximum thermal power.". I could find some old docs[3] that did give the maximum power, but can't seem to find any on their recent CPUs. [1] http://www.intel.com/content/dam/doc/white-paper/resources-xeon-measuring-processor-power-paper.pdf http://www.intel.com/content/dam/doc/white-paper/resources-x... [2] ftp://ftp.sgi.com/public/Technical%20Support/Pdf%20files/AMD/26633_5649.pdf [3] http://hackipedia.org/Platform/x86/AMD/AMD%20Thermal,%20Mechanical,%20and%20Chassis%20Cooling%20Design%20Guide%20(January%202002).pdf http://hackipedia.org/Platform/x86/AMD/AMD%20Thermal,%20Mech...
        msimpson 10y ago
        Refer to the following, taken from that guide: 4.1 T_CASE and DTS-Based Thermal Specification Implementation Thermal solutions should be sized such that the processor complies to the T_CASE thermal profile all the way up to TDP, because, when all cores are active, a thermal solution sized as such will have the capacity to meet the DTS thermal profile, by design. When all cores are not active or when Intel Turbo Boost Technology is active, attempting to comply with the DTS thermal profile may drive system fans to speeds higher than the fan speed required to comply with the T_CASE thermal profile at TDP. In cases where thermal solutions are undersized, and the processor does not comply with the T_CASE thermal profile at TDP, compliance can occur when the processor power is kept lower than TDP, AND the actual T_CASE is below the T_CASE thermal profile at that lower power. In most situations, implementation of DTS thermal profile can reduce average fan power and improve acoustics, as compared to T_CONTROL -based fan speed control. When DTS < T_CONTROL , the processor is compliant, and T_CASE and DTS thermal profiles can be ignored. 5.3.1 Intel ® Turbo Boost Technology Intel ® Turbo Boost Technology is a feature available on certain Intel ® Xeon ® processor E5-1600 and E5-2600 v3 product families SKUs that opportunistically, and automatically allows the processor to run faster than the marked frequency if the part is operating below certain power and temperature limits. With Turbo Boost enabled, the instantaneous processor power can exceed TDP for short durations resulting in increased performance. (http://www.intel.com/content/dam/www/public/us/en/documents/guides/xeon-e5-v3-thermal-guide.pdf) This means that as long as you give the CPU a thermal solution capable of dissipating a thermal wattage equivalent to the CPU's temperature, at its case, when it reaches TDP, you're good. However, if you push the processor into Turbo Boost (like Atwood did with mprime), the CPU can exceed TDP for short durations. And, while all this is happening, the Thermal Control Circuit (TCC) is managing the thermal output by adjusting the clock, frequency, and input voltage automatically so the CPU stays away from operational limits. Therefore, if you intend to run this CPU under a sustained heavy load you must supply a thermal solution beyond TDP. Intel literally spelled that out in this PDF which they linked from their TDP definition on every CPU specification page. Now, in terms of power consumption. You must consider the entire system as the CPU is going to manage itself to fit its environment given the TCC. That is why Intel suggests you measure overall consumption for the server using a power meter as each implementation can yield different results. Therefore, what Atwood is doing is actually Intel's recommendation for considering actual power consumption. He, as I originally stated who knows how many replies ago, is making the mistake of directly equating power consumption to heat dissipation. When all you can really be sure of is that if a CPU consumes 1 watt of power it can dissipate up to the same in heat. But, as thermal dynamics will tell you, it will always be a bit less on the output as nothing is 100% efficient. Therefore, all Atwood's test proves is an Intel® Xeon® Processor E5-1650 v3 has the potential to dissipate up to 250 watts of heat while in Turbo, given its recorded power consumption, in that specific computer configuration while running mprime. Nothing more, nothing less. That is my point.

ksk 10y ago

Practically, sure, you pretty much have to do whatever it takes to get it working. But its not like we're talking about trade secrets here. They simply have to release a coherent definition of what they consider a typical load. I get your point, but nothing wrong in drawing attention to the specs being incomplete to the point of being useless.

msimpson 10y ago
> They simply have to release a coherent definition of what they consider a typical load. Have fun getting AMD and Intel to agree on something. > I get your point, but nothing wrong in drawing attention to the specs being incomplete to the point of being useless. Vague or averaged is not useless.
- ksk 10y ago
  What does Intel documenting their own specs have to do with AMD?
  - msimpson 10y ago
    TDP is used by multiple manufacturers, so getting a "coherent definition" is going to take work. If you want to understand more about the thermal specs from only Intel. You can read their thermal guide: http://www.intel.com/content/dam/www/public/us/en/documents/guides/xeon-e5-v3-thermal-guide.pdf http://www.intel.com/content/dam/www/public/us/en/documents/...
    - ksk 10y ago
      Sorry, I don't understand your point. Each vendor already defines it in their own way. The point of the article is that without proper guidance you end up guessing. I'm afraid the guide you linked to doesn't help much. Intel confusingly tells us "TDP: Thermal solution should be designed to dissipate this target power level. TDP is not the maximum power that the processor can dissipate." So according to Intel [1] - "The best way to measure a server’s power consumption is the power meter, an inexpensive tool that is plugged into the wall, and then your device, like a server, can be plugged into the power meter. The meter displays the wattage drawn "at the wall" and allows you to analyze the power consumption under a variety of different utilization levels.". Strange. I was looking up docs on AMD. They seem[2] to kinda get it: "To allow optimal reliability of the AMD Opteron and AMD Athlon 64 processor-based systems, the thermal and cooling solution should dissipate heat from a processor operating at its maximum thermal power.". I could find some old docs[3] that did give the maximum power, but can't seem to find any on their recent CPUs. [1] http://www.intel.com/content/dam/doc/white-paper/resources-xeon-measuring-processor-power-paper.pdf http://www.intel.com/content/dam/doc/white-paper/resources-x... [2] ftp://ftp.sgi.com/public/Technical%20Support/Pdf%20files/AMD/26633_5649.pdf [3] http://hackipedia.org/Platform/x86/AMD/AMD%20Thermal,%20Mechanical,%20and%20Chassis%20Cooling%20Design%20Guide%20(January%202002).pdf http://hackipedia.org/Platform/x86/AMD/AMD%20Thermal,%20Mech...
      - msimpson 10y ago
        Refer to the following, taken from that guide: 4.1 T_CASE and DTS-Based Thermal Specification Implementation Thermal solutions should be sized such that the processor complies to the T_CASE thermal profile all the way up to TDP, because, when all cores are active, a thermal solution sized as such will have the capacity to meet the DTS thermal profile, by design. When all cores are not active or when Intel Turbo Boost Technology is active, attempting to comply with the DTS thermal profile may drive system fans to speeds higher than the fan speed required to comply with the T_CASE thermal profile at TDP. In cases where thermal solutions are undersized, and the processor does not comply with the T_CASE thermal profile at TDP, compliance can occur when the processor power is kept lower than TDP, AND the actual T_CASE is below the T_CASE thermal profile at that lower power. In most situations, implementation of DTS thermal profile can reduce average fan power and improve acoustics, as compared to T_CONTROL -based fan speed control. When DTS < T_CONTROL , the processor is compliant, and T_CASE and DTS thermal profiles can be ignored. 5.3.1 Intel ® Turbo Boost Technology Intel ® Turbo Boost Technology is a feature available on certain Intel ® Xeon ® processor E5-1600 and E5-2600 v3 product families SKUs that opportunistically, and automatically allows the processor to run faster than the marked frequency if the part is operating below certain power and temperature limits. With Turbo Boost enabled, the instantaneous processor power can exceed TDP for short durations resulting in increased performance. (http://www.intel.com/content/dam/www/public/us/en/documents/guides/xeon-e5-v3-thermal-guide.pdf) This means that as long as you give the CPU a thermal solution capable of dissipating a thermal wattage equivalent to the CPU's temperature, at its case, when it reaches TDP, you're good. However, if you push the processor into Turbo Boost (like Atwood did with mprime), the CPU can exceed TDP for short durations. And, while all this is happening, the Thermal Control Circuit (TCC) is managing the thermal output by adjusting the clock, frequency, and input voltage automatically so the CPU stays away from operational limits. Therefore, if you intend to run this CPU under a sustained heavy load you must supply a thermal solution beyond TDP. Intel literally spelled that out in this PDF which they linked from their TDP definition on every CPU specification page. Now, in terms of power consumption. You must consider the entire system as the CPU is going to manage itself to fit its environment given the TCC. That is why Intel suggests you measure overall consumption for the server using a power meter as each implementation can yield different results. Therefore, what Atwood is doing is actually Intel's recommendation for considering actual power consumption. He, as I originally stated who knows how many replies ago, is making the mistake of directly equating power consumption to heat dissipation. When all you can really be sure of is that if a CPU consumes 1 watt of power it can dissipate up to the same in heat. But, as thermal dynamics will tell you, it will always be a bit less on the output as nothing is 100% efficient. Therefore, all Atwood's test proves is an Intel® Xeon® Processor E5-1650 v3 has the potential to dissipate up to 250 watts of heat while in Turbo, given its recorded power consumption, in that specific computer configuration while running mprime. Nothing more, nothing less. That is my point.