5 ms·

Yet, he is not measuring the Vcore going into the CPU. He is measuring the overall wattage consumed by the PSU at the outlet using a Kill-a-Watt. This contains

Yet, he is not measuring the Vcore going into the CPU. He is measuring the overall wattage consumed by the PSU at the outlet using a Kill-a-Watt. This contains a lot more draw than just the CPU, itself. That's an overwhelming lack of concern for a wealth of other variables that can amount to tens of watts. So to be more concise: Overall energy consumption of a computer does not equate to only the TDP of the CPU, itself.

lightedman 10y ago
"This contains a lot more draw than just the CPU, itself." Not really. Modern RAM uses a couple watts. Fans use at typical 2.5w each. Hard Drives only a few watts (SSD variety.) The PSU in servers tends to be fairly efficient, maybe losing 50-ish watts due to heat, and they run more efficiently at lower draws than higher draws. So using a Kill-A-Watt gives you a better idea of how much power the CPU is truly sucking down (especially when a GPU isn't installed.) This is how I catch LED lighting companies lying about their actual power usage on their lights.
- msimpson 10y ago
  When you're arguing over a 110 watt difference, 50 watts lost as heat in the PSU is not insignificant and certainly enough to skew a test.
  - ksk 10y ago
    The author is comparing how off the numbers are from the stated specs, not establishing the accuracy of individual figures. If the extraneous power-draw is reasonably constant, it can provide an interesting comparison.
    - msimpson 10y ago
      The author is comparing how off overall power consumption is from the stated thermal design power under a sustained, heavy load; which is not what TDP is intended to measure ... "TDP is not the maximum power that the processor can dissipate." -- Intel Keep in mind that TDP is only a target number for typical use, not mprime. Not to mention Intel and AMD define it differently, see: http://www.silentpcreview.com/article169-page3.html http://www.silentpcreview.com/article169-page3.html "Intel is listing TDP numbers that are significantly lower than the actual maximum power draw of their CPUs." That article is THIRTEEN YEARS OLD!
      - ksk 10y ago
        Yes, so the obvious point for the reader to glean is that Intel is sneaky about using different ways of calculating TDP for different products. Why they would do that is anyones guess. Obviously they wouldn't want to give out false information to system builders who might end up with underpowered PSUs and overheating CPUs.
        msimpson 10y ago
        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?
  - lightedman 10y ago
    That 50 watts only happens under a fully-loaded PSU scenario. 500w PSU at full load would deliver at 80+ rating ~400w. That same PSU just rolling barely enough equipment to keep a processor fully fed might draw 300w from the PSU, of which maybe 20w of that is wasted. This is basic PSU and power supply principle.
    - msimpson 10y ago
      As I said, "variables that can amount to TENS of watts."
nucleardog 10y ago
> Unfortunately, here's what I actually measured with my trusty Kill-a-Watt for each server build as I performed my standard stability testing, with completely identical parts except for the CPU: The two CPUs were in identical test rigs. There is a 80W difference changing only the CPU. While you can expect some of this is lost in the PSU, simple fact is more power is ending up inside the computer and it has nowhere to go but out as heat. The most reasonable explanation given otherwise identical builds would be to expect this difference to be due to the changed component. So if we assume that Intel's 4-core is actually 140W TDP, then there's no way this 6-core can also be 140W. Yes, this isn't an exact, scientific test, but it's certainly reliable enough to say "this 6-core processor is emitting more heat than the 4-core, although they are rated identically" which it seems to me was the only point he was trying to make given the context which was "two more cores, slightly lower clock speed, that might be an okay tradeoff - OH WAIT, MORE HEAT".
- msimpson 10y ago
  > So if we assume that Intel's 4-core is actually 140W TDP, then there's no way this 6-core can also be 140W. Why? How can you say that under typical usage the thermal dissipation for both chips isn't the same? Atwood's numbers measure overall power consumption while idle and under heavy load with mprime, neither of which is what TDP seeks to measure. TDP is like fuel economy for cars. You don't claim it's a lie when you go one hundred and fifty miles an hour for 20 miles and burn two gallons of gas. You simply realize those highway numbers are meant for more of a sixty mile per hour journey over the same distance.
  - nucleardog 10y ago
    Okay: Yes, TDP is an inexactly defined and meaningless term and while to the layman it would generally be understood to have some relation to the heat emitted by the CPU during normal operation, it's possible that both chips in fact only generate 1W of heat and were given a 140W TDP because Intel had a pre-existing cooling solution and a warehouse full of spare parts. Yes, you are correct on the semantics. Power consumption has no relation to TDP because heat generated has no defined relation to TDP. However, given any meaningfully bounded definition of TDP, the case is still made that the TDP of these chips should be dissimilar. The later numbers show that under full load the power draw at the wall increases by 20W/core used. Unless your "typical load" used for determining TDP does not actually make use of the full number of cores (which I would think could be fine for a desktop processor, certainly not a server) then it's clear that the heat generated by these two processors should be dissimilar under any load. If the 4 core actually needs to dissipate 140W under a typical use case, then the 6 core should absolutely need to dissipate more unless the "typical use case" is uselessly applied. If we want to talk cars... Let's say I sell a base model with a top speed of 80mph, and a sport model with a top speed of 120mph. But I tell you you only need to put 80mph rated tires on the sport model because that's as fast as a typical person drives. Would you really claim that the sport model's tires are correctly rated? Would you not be surprised when you drove 100mph in the sport model and the tires exploded? Why on Earth would anyone even buy the sport model if it's crippled to nearly the same performance as the base model?

lightedman 10y ago

"This contains a lot more draw than just the CPU, itself." Not really. Modern RAM uses a couple watts. Fans use at typical 2.5w each. Hard Drives only a few watts (SSD variety.) The PSU in servers tends to be fairly efficient, maybe losing 50-ish watts due to heat, and they run more efficiently at lower draws than higher draws. So using a Kill-A-Watt gives you a better idea of how much power the CPU is truly sucking down (especially when a GPU isn't installed.) This is how I catch LED lighting companies lying about their actual power usage on their lights.

msimpson 10y ago
When you're arguing over a 110 watt difference, 50 watts lost as heat in the PSU is not insignificant and certainly enough to skew a test.
- ksk 10y ago
  The author is comparing how off the numbers are from the stated specs, not establishing the accuracy of individual figures. If the extraneous power-draw is reasonably constant, it can provide an interesting comparison.
  - msimpson 10y ago
    The author is comparing how off overall power consumption is from the stated thermal design power under a sustained, heavy load; which is not what TDP is intended to measure ... "TDP is not the maximum power that the processor can dissipate." -- Intel Keep in mind that TDP is only a target number for typical use, not mprime. Not to mention Intel and AMD define it differently, see: http://www.silentpcreview.com/article169-page3.html http://www.silentpcreview.com/article169-page3.html "Intel is listing TDP numbers that are significantly lower than the actual maximum power draw of their CPUs." That article is THIRTEEN YEARS OLD!
    - ksk 10y ago
      Yes, so the obvious point for the reader to glean is that Intel is sneaky about using different ways of calculating TDP for different products. Why they would do that is anyones guess. Obviously they wouldn't want to give out false information to system builders who might end up with underpowered PSUs and overheating CPUs.
      - msimpson 10y ago
        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?
- lightedman 10y ago
  That 50 watts only happens under a fully-loaded PSU scenario. 500w PSU at full load would deliver at 80+ rating ~400w. That same PSU just rolling barely enough equipment to keep a processor fully fed might draw 300w from the PSU, of which maybe 20w of that is wasted. This is basic PSU and power supply principle.
  - msimpson 10y ago
    As I said, "variables that can amount to TENS of watts."

nucleardog 10y ago

> Unfortunately, here's what I actually measured with my trusty Kill-a-Watt for each server build as I performed my standard stability testing, with completely identical parts except for the CPU: The two CPUs were in identical test rigs. There is a 80W difference changing only the CPU. While you can expect some of this is lost in the PSU, simple fact is more power is ending up inside the computer and it has nowhere to go but out as heat. The most reasonable explanation given otherwise identical builds would be to expect this difference to be due to the changed component. So if we assume that Intel's 4-core is actually 140W TDP, then there's no way this 6-core can also be 140W. Yes, this isn't an exact, scientific test, but it's certainly reliable enough to say "this 6-core processor is emitting more heat than the 4-core, although they are rated identically" which it seems to me was the only point he was trying to make given the context which was "two more cores, slightly lower clock speed, that might be an okay tradeoff - OH WAIT, MORE HEAT".

msimpson 10y ago
> So if we assume that Intel's 4-core is actually 140W TDP, then there's no way this 6-core can also be 140W. Why? How can you say that under typical usage the thermal dissipation for both chips isn't the same? Atwood's numbers measure overall power consumption while idle and under heavy load with mprime, neither of which is what TDP seeks to measure. TDP is like fuel economy for cars. You don't claim it's a lie when you go one hundred and fifty miles an hour for 20 miles and burn two gallons of gas. You simply realize those highway numbers are meant for more of a sixty mile per hour journey over the same distance.
- nucleardog 10y ago
  Okay: Yes, TDP is an inexactly defined and meaningless term and while to the layman it would generally be understood to have some relation to the heat emitted by the CPU during normal operation, it's possible that both chips in fact only generate 1W of heat and were given a 140W TDP because Intel had a pre-existing cooling solution and a warehouse full of spare parts. Yes, you are correct on the semantics. Power consumption has no relation to TDP because heat generated has no defined relation to TDP. However, given any meaningfully bounded definition of TDP, the case is still made that the TDP of these chips should be dissimilar. The later numbers show that under full load the power draw at the wall increases by 20W/core used. Unless your "typical load" used for determining TDP does not actually make use of the full number of cores (which I would think could be fine for a desktop processor, certainly not a server) then it's clear that the heat generated by these two processors should be dissimilar under any load. If the 4 core actually needs to dissipate 140W under a typical use case, then the 6 core should absolutely need to dissipate more unless the "typical use case" is uselessly applied. If we want to talk cars... Let's say I sell a base model with a top speed of 80mph, and a sport model with a top speed of 120mph. But I tell you you only need to put 80mph rated tires on the sport model because that's as fast as a typical person drives. Would you really claim that the sport model's tires are correctly rated? Would you not be surprised when you drove 100mph in the sport model and the tires exploded? Why on Earth would anyone even buy the sport model if it's crippled to nearly the same performance as the base model?