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Thread: Energy note- TDP Intel/AMD

  1. #1
    Xtreme Cruncher Otis11's Avatar
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    Energy note- TDP Intel/AMD

    This ought to make you happy PG... I was cruising the HW forums and found flippin_waffles had posted this. Puts some things in perspective. Just thought I would spread the work since there are a couple threads dedicated to energy vs performance for crunching!

    It's ok to call me a liar, but keep in mind that since I work in the industry, I know a lot more than the average person when it comes to these things. I don't make things up because I everything that I do can be tracked back directly to me. The internet is anonymous but I post as myself, so I need an extra level of scrutiny.

    You are mistaken about TDP, because both companies deal with it differently.

    Intel has 2 power levels: TDP and max power, (and now a third, "sustained power").

    Take a look at the X5570 to see:

    http://www.cpu-world.com/CPUs/Xeon/I...602X5570).html

    Maximum power dissipation (W) 197.97; 155.56 (sustained)
    Thermal Design Power (W) 95

    So the way Intel always measured it in the past, Max power is the maximum power that a CPU can draw. Every transistor firing in a worst case scenario.

    TDP is a de-rated value (used to be 80%, but it has been creeping down which is bad). Intel would take the maximum power, assume that the processor would throttle the clock down and then take that measurement (of a throttled processor) as the "TDP".

    Since that time they have added a maximum sustained, maybe you can ask them what that means. I am assuming that max power is a spike power and that sustained is something that lasts more than a few milliseconds.

    Regardless, the maximum power that the processor could conceivably draw is 197W.

    Our TDP is equivalent to their max power, it is the maximum power the processor could draw, every transistor firing in a worst case scenario.

    Our ACP is average CPU power. We run standard workloads, run them at 100% utilization and measure power.

    Intel is not real open about max power. They used to post it online, but when they started getting pressure from AMD about those max power ratings, they stopped showing up online.

    I'd love to have someone from Intel come here to debate this topic, because at this point, the specs (which they try to keep private) are not in their favor.

    In designing a system to max power (which you have to do), we are not 42w disavantaged, we are actually 60w advantaged.

    We do release max power. It is called TDP. http://en.wikipedia.org/wiki/Thermal_Design_Power

    The reason the thermal design sheet lists TDP is because that is what you use to design systems. TDP is designed for system builders and OEMs. ACP is designed for customers in figuring out what they need for the data center.

    ACP came into being a few years back because our TDP was 95W and it was rare that we ever had a part that even got above 50W. Customers were complaining that they were budgeting their racks for a certian amount of power, assuming 95W, and then ending up heavily under utilized. We were getting a lot of complaints from customers that we were too conservative and that this was leading to too much inefficiency in their data centers. I was on the receiving end of a lot of these conversations and they were not pleasant as data center floor space was the most expensive real estate in the building.

    If you want a simple rule of thumb, use the following.

    Most power a system can draw:
    Intel = Max power
    AMD = TDP

    Typical power draw for standard applications:
    Intel = TDP
    AMD = ACP

    If you are asking "why doesn't AMD just use TDP like the rest of the world" then you are on to something. We actually do. If you bother to go back to the wikipedia link above, you'll see TDP defined as:


    Quote:
    The thermal design power (TDP), sometimes called thermal design point, represents the maximum amount of power the cooling system in a computer is required to dissipate

    That sounds a lot like how AMD defines TDP, but that also sounds like how Intel defines max power. So, in reality, the "hoky" measurement is actually Intel's TDP because it does not represent what the rest of the industry means when they say TDP.
    http://www.semiaccurate.com/forums/s...p?t=651&page=9

  2. #2
    Xtreme Cruncher Chumbucket843's Avatar
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    140gflops@130 watts = win

  3. #3
    Xtreme Cruncher Otis11's Avatar
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    Quote Originally Posted by Chumbucket843 View Post
    140gflops@130 watts = win
    What?

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    Xtreme Cruncher PoppaGeek's Avatar
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    Good info Otis.

  5. #5
    Xtreme Cruncher PoppaGeek's Avatar
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    Quote Originally Posted by Chumbucket843 View Post
    140gflops@130 watts = win
    GPU?

  6. #6
    Xtreme Cruncher Chumbucket843's Avatar
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    Quote Originally Posted by PoppaGeek View Post
    GPU?
    no thats core i7 peak flops. i heart mine. its almost as fast as dual socket core 2 systems on bigadv when OCed.
    Last edited by Chumbucket843; 10-05-2009 at 03:39 PM.

  7. #7
    Xtreme Cruncher PoppaGeek's Avatar
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    So you were just chumming hoping for a bite?

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    Xtreme Addict ctgilles's Avatar
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    Quote Originally Posted by Chumbucket843 View Post
    no thats core i7 peak flops. i heart mine. its almost as fast as dual socket core 2 systems on bigadv when OCed.
    I'm doing b&e at Intel tomorrow to steal a hexa i9
    24 core Xeon:
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  9. #9
    Back from the Dead jcool's Avatar
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    200W out of an X5570? I have two, and they don't draw that much together while crunching
    Intels TDP can be off, yes, but it's no more off than AMDs ACP rating.. for example, my Quad 8347HE has an ACP of 4x 55W.. if that would be true, the mobo would eat 130W on its own (factoring in PSU efficiency, rams, fans, etc)

    For me, theoretical numbers will always be what they are - pure theory.
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