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AMD's not really any better when it comes to fudging specs. At least Intel CPUs actually limit their sustained power draw to the TDP when running in their facto

by magila 6y ago

AMD's not really any better when it comes to fudging specs. At least Intel CPUs actually limit their sustained power draw to the TDP when running in their factory default configuration, even if enthusiast motherboards usually override it. AMD CPUs OTOH run significantly higher power than their spec'd TDP right out-of-the box. For example, that "105 W" 3900X actually ships with a power limit of 142 W and it is quite capable of sustaining that under an all-core load. AMD's turbo numbers are also pure fantasy. If AMD rated turbo frequencies the same way Intel did that 3900X would have a max turbo of 4.2 or 4.3 GHz instead of 4.6 GHz. When Intel says their CPU can hit a given turbo frequency they mean it will actually hit that and stay there so long as power/temperature remains within limits. Meanwhile AMD CPUs may-or-may not ever hit their max turbo frequency, and if they do it's only for a fraction of a second while off full load. The outrage over Intel CPU's power consumption is pretty silly when you realize that the only reason AMD CPUs don't draw just as much is because their chips would explode if you tried to pump that much power into them. If you care about power consumption just set your power limits as desired and Intel CPUs will deliver perfectly reasonable power efficiency and performance.

throwaway2048 6y ago
40% fudging is still significantly better than 100% or 200%
dralley 6y ago
>>AMD CPUs OTOH run significantly higher power than their spec'd TDP right out-of-the box. For example, that "105 W" 3900X actually ships with a power limit of 142 W and it is quite capable of sustaining that under an all-core load. I'm pretty sure you've got that exactly reversed, AMD's power draw tends to stay closer to the rated TDP than Intel's. >>The outrage over Intel CPU's power consumption is pretty silly when you realize that the only reason AMD CPUs don't draw just as much is because their chips would explode if you tried to pump that much power into them. If you care about power consumption just set your power limits as desired and Intel CPUs will deliver perfectly reasonable power efficiency and performance. I'm not even sure what this means. AMD CPUs are on a more advanced and physically smaller process, with smaller wires, and a different voltage-frequency-response curve. Of course they would "explode" if you try to pump them with voltages that the process isn't designed to operate with, that the Intel CPU with it's larger process can handle. But the power draw isn't really the "point" of the CPU -- performance is. Imagine thinking that the Pentium 4 or Bulldozer was better than their contemporaries because they were capable of drawing incredible amounts of power.
- magila 6y ago
  > I'm pretty sure you've got that exactly reversed, AMD's power draw tends to stay closer to the rated TDP than Intel's. I was talking about the CPUs in their factory default configuration. Intel CPUs default to limiting their sustained power draw to exactly their TDP, AMD CPUs meanwhile run significantly higher. Where Intel CPUs will draw more is when you disable the power limits, but that power buys you extra frequency over what AMD is capable of. > That's like complaining that speaker wire is deficient because you can't use it to charge an electric car. It's a CPU, not a space heater -- how much power it can draw isn't the point, performance is. Yes, and Intel CPUs achieve significantly higher frequency, and thus per-thread performance, in exchange for that higher power. With Intel you have the option of running high power/high frequency or lower power/high efficiency. With AMD you don't get the former option due to limitations of the fabrication process used. Somehow this has come to be considered a win for AMD.
  - kllrnohj 6y ago
    > Intel CPUs default to limiting their sustained power draw to exactly their TDP No, no they don't. That's a motherboard setting not a CPU one, and basically no desktop motherboard at least follows Intel's "recommendation" out of the box.
    - magila 6y ago
      > No, no they don't. Yes, they do. The power limits are set in MSRs within the CPU and the CPU has default values for those MSRs. > basically no desktop motherboard at least follows Intel's "recommendation" out of the box. Wrong again. Motherboards using chipsets other than the Z series typically do not change the power limits unless the user explicitly sets them. These days even Z series boards do not change the power limits unless the user enables at least one overclocking feature, e.g. XMP. This is how the motherboard manufacturers technically follow Intel's specs while actually running out-of-spec with the settings most enthusiast users use.
sq_ 6y ago
> AMD's turbo numbers are also pure fantasy. I'm pretty certain that I remember watching videos from GN, LTT, or Bitwit (can't recall which) where they noted that AMD chips were turboing up to a few hundred MHz above the specced numbers.
- Dylan16807 6y ago
  The most recent generation had turbo numbers that were about 100MHz higher than they should be, and it was difficult or impossible to reach the stated number on most chips, especially on launch or near-launch BIOS versions.
  - tracker1 6y ago
    Most came close, but you're right... Of course, Intel's max boost is the same, and unlikely in most consumer systems. The AMD bios's were updated and do get better boosts now, but really in short bursts. That said, they do incredibly well for most circumstances and depending on your use, a much better option at all price points, except for some gaming at the ~$500 mark. I'd still take an R9 3900X over an i9 *900K series. Using a 3950X now, no plans to upgrade for 3-5 years.
- magila 6y ago
  Those youtubers are measuring "turboing" by looking at the maximum frequency column in HWiNFO. So they consider a CPU to have hit a frequency even if it only touched it for a single millisecond during a minutes long benchmark run. For AMD CPUs the average frequency is typically significantly lower.
  - sq_ 6y ago
    Maybe smaller channels, but I find that most of the bigger ones (especially GamersNexus) put a ton of effort into having a good, repeatable process for in-depth looks at performance. Certainly on par with Anandtech or any of the other typically trusted review sites.
    - 6y ago
jotm 6y ago
> When Intel says their CPU can hit a given turbo frequency they mean it will actually hit that and stay there so long as power/temperature remains within limits. Have you actually tried to do that? When Intel says their CPU can hit a Turbo frequency, it's usually pure fantasy because they can't actually do it within the power/temp constraints. Yes, they'll get to 5-whatever GHz on maybe half the cores if you're lucky, but full all-core load at the top stated Turbo? No chip will stay there, it will throttle down, likely by a lot. And AVX loads will bring it to, or close to, maximum non-turbo clocks, that's how hot they run. It could maybe be done with extremely good cooling and undervolting, and completely removing power limits (in which case it will probably consume close to 500W if it doesn't fry something first :D).
- rowanG077 6y ago
  Actually heavy AVX loads can even force an Intel CPU below it's base clock.

by magila 6y ago

throwaway2048 6y ago

40% fudging is still significantly better than 100% or 200%

dralley 6y ago

>>AMD CPUs OTOH run significantly higher power than their spec'd TDP right out-of-the box. For example, that "105 W" 3900X actually ships with a power limit of 142 W and it is quite capable of sustaining that under an all-core load. I'm pretty sure you've got that exactly reversed, AMD's power draw tends to stay closer to the rated TDP than Intel's. >>The outrage over Intel CPU's power consumption is pretty silly when you realize that the only reason AMD CPUs don't draw just as much is because their chips would explode if you tried to pump that much power into them. If you care about power consumption just set your power limits as desired and Intel CPUs will deliver perfectly reasonable power efficiency and performance. I'm not even sure what this means. AMD CPUs are on a more advanced and physically smaller process, with smaller wires, and a different voltage-frequency-response curve. Of course they would "explode" if you try to pump them with voltages that the process isn't designed to operate with, that the Intel CPU with it's larger process can handle. But the power draw isn't really the "point" of the CPU -- performance is. Imagine thinking that the Pentium 4 or Bulldozer was better than their contemporaries because they were capable of drawing incredible amounts of power.

magila 6y ago
> I'm pretty sure you've got that exactly reversed, AMD's power draw tends to stay closer to the rated TDP than Intel's. I was talking about the CPUs in their factory default configuration. Intel CPUs default to limiting their sustained power draw to exactly their TDP, AMD CPUs meanwhile run significantly higher. Where Intel CPUs will draw more is when you disable the power limits, but that power buys you extra frequency over what AMD is capable of. > That's like complaining that speaker wire is deficient because you can't use it to charge an electric car. It's a CPU, not a space heater -- how much power it can draw isn't the point, performance is. Yes, and Intel CPUs achieve significantly higher frequency, and thus per-thread performance, in exchange for that higher power. With Intel you have the option of running high power/high frequency or lower power/high efficiency. With AMD you don't get the former option due to limitations of the fabrication process used. Somehow this has come to be considered a win for AMD.
- kllrnohj 6y ago
  > Intel CPUs default to limiting their sustained power draw to exactly their TDP No, no they don't. That's a motherboard setting not a CPU one, and basically no desktop motherboard at least follows Intel's "recommendation" out of the box.
  - magila 6y ago
    > No, no they don't. Yes, they do. The power limits are set in MSRs within the CPU and the CPU has default values for those MSRs. > basically no desktop motherboard at least follows Intel's "recommendation" out of the box. Wrong again. Motherboards using chipsets other than the Z series typically do not change the power limits unless the user explicitly sets them. These days even Z series boards do not change the power limits unless the user enables at least one overclocking feature, e.g. XMP. This is how the motherboard manufacturers technically follow Intel's specs while actually running out-of-spec with the settings most enthusiast users use.

sq_ 6y ago

> AMD's turbo numbers are also pure fantasy. I'm pretty certain that I remember watching videos from GN, LTT, or Bitwit (can't recall which) where they noted that AMD chips were turboing up to a few hundred MHz above the specced numbers.

Dylan16807 6y ago
The most recent generation had turbo numbers that were about 100MHz higher than they should be, and it was difficult or impossible to reach the stated number on most chips, especially on launch or near-launch BIOS versions.
- tracker1 6y ago
  Most came close, but you're right... Of course, Intel's max boost is the same, and unlikely in most consumer systems. The AMD bios's were updated and do get better boosts now, but really in short bursts. That said, they do incredibly well for most circumstances and depending on your use, a much better option at all price points, except for some gaming at the ~$500 mark. I'd still take an R9 3900X over an i9 *900K series. Using a 3950X now, no plans to upgrade for 3-5 years.
magila 6y ago
Those youtubers are measuring "turboing" by looking at the maximum frequency column in HWiNFO. So they consider a CPU to have hit a frequency even if it only touched it for a single millisecond during a minutes long benchmark run. For AMD CPUs the average frequency is typically significantly lower.
- sq_ 6y ago
  Maybe smaller channels, but I find that most of the bigger ones (especially GamersNexus) put a ton of effort into having a good, repeatable process for in-depth looks at performance. Certainly on par with Anandtech or any of the other typically trusted review sites.
  - 6y ago

jotm 6y ago

> When Intel says their CPU can hit a given turbo frequency they mean it will actually hit that and stay there so long as power/temperature remains within limits. Have you actually tried to do that? When Intel says their CPU can hit a Turbo frequency, it's usually pure fantasy because they can't actually do it within the power/temp constraints. Yes, they'll get to 5-whatever GHz on maybe half the cores if you're lucky, but full all-core load at the top stated Turbo? No chip will stay there, it will throttle down, likely by a lot. And AVX loads will bring it to, or close to, maximum non-turbo clocks, that's how hot they run. It could maybe be done with extremely good cooling and undervolting, and completely removing power limits (in which case it will probably consume close to 500W if it doesn't fry something first :D).

rowanG077 6y ago
Actually heavy AVX loads can even force an Intel CPU below it's base clock.