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Are people still impressed by low TDP numbers? Everyone can manipulate that number to anything you want by changing the base clock. Intel could sell the 9900K w

Are people still impressed by low TDP numbers? Everyone can manipulate that number to anything you want by changing the base clock. Intel could sell the 9900K with a 25 W TDP by saying the base clock is 1200 MHz, AMD could do the same. (I mean the 95 W TDP for the 9900K is already a meme.) It's just gonna be exactly the same CPU as the 3900X, just a slightly worse binned version.

JamesMcMinn 7y ago
Intel measure the TDP based on the base clock, yes. However AMD seem to measure it based on what the CPU is likely to draw with boost clocks over a sustained period of time, so their TDP numbers are quite accurate.
- pingyong 7y ago
  The 3900X still uses ~140 W at full load with a 105 W TDP. And still just like Intel, if you limit the clock speeds you can make it use 105 W, 65 W, or 35 W at full load, just like with Intel chips. AMD calculates the TDP a bit differently, but nothing really changes fundamentally. All CPUs in a generation are essentially the same chip, TDP is completely irrelevant.
  - jankotek 7y ago
    Not the same chip, quality differs, some units would require higher voltage for the same frequency. Some CPUs are more power efficient because they can take lover voltage.
    - pingyong 7y ago
      Yeah and those chips are typically the ones being sold as higher TDP chips.
  - pizza234 7y ago
    For users who have a fixed TDP budget, there's a substantial difference. The AMD power calculation is not "bit different", it's Intel who is cheating big time. On a system with constrained power values, those who buy Intel will suffer a substantially higher hit than those who buy AMD.
    - pingyong 7y ago
      > For users who have a fixed TDP budget, there's a substantial difference. I really, really don't see how. Both TDPs have very little connection to how much power the chips actually pulls at full load. 105 to 140 isn't useful in any way. If it was 107, sure, but 140 is 1/3rd higher than "spec" (I write "spec" because TDP isn't supposed to tell you what the highest power draw possible is if your cooling can dissipate more than the TDP in the first place, people just somehow seem to use it that way). If you have a fixed TDP cooler, all you have to do is put that cooler on CPUs and see which ones will be faster. No looking at the specs required. If you have a fixed power consumption budget, but a better cooler, all you have to do is downclock until the CPU stays within that budget and then compare performance. Again, spec wasn't useful.
  - JamesMcMinn 7y ago
    140W is considerably closer to the stated 105W TDP value of the 3900X than a "95W" 9900k which can easily pull down 180W. Whilst I agree that TDP shouldn't be taken as gospel, at least in AMDs case, it can be a useful approximation the amount of heat generated (and thus power draw). If you then compare the actual performance per watt, a 12 core CPU at 3.1 base / 4.2 boost pulling down approximately 65W is very impressive. Something similar from Intel (in terms of number of cores at even just the 3.1 base frequency) would likely have a TDP of at least 120W.
    - pingyong 7y ago
      >140W is considerably closer Closer, yes, but more useful? Both are off by a mile - not to mention that TDP isn't supposed to tell you a chip's maximum power consumption in the first place. It's supposed to tell you how good your cooler has to be to sustain base clocks / single core turbo, or in AMD's case, to sustain base clocks and some? boost clocks for a limited time. >If you then compare the actual performance per watt Performance per watt can certainly be interesting for many people. Performance per watt just isn't connected to TDP. The 3900X (105 W TDP) has higher performance per watt than the 9900K (95 W TDP). Probably at any frequency - although potentially the 3900X can't clock down as much. The 9900K can run Cinebench without a cooler after all (at least the 8700K can, so I'd suspect the 9900K can do that too), while the AMD processors can't. Also, the 3900 (65 W TDP) has the same performance per watt as the 3900X (105 W TDP), if you let them run at the same clock speeds.
      - juergbi 7y ago
        Ryzen SKUs with a 105W TDP have a power limit (PPT) of 142W at stock. 65W TDP SKUs have a power limit of 88W. I.e., while these CPUs are allowed to use more power than their TDP, it's limited to 35% above the TDP. This means that the advertised TDP is not just an arbitrary number they slap on the package.
        pingyong 7y ago
        It's not an arbitrary number on Intel's CPUs either, it's just still not very useful. Or at least it's not useful as an indicator of some sort of technological progress. If you limit a 3900X to 3900 clock speeds and voltages, it's going to behave exactly the same.
- rasz 7y ago
  AMD used to do that until Zen 2. With new generation AMD joined intel in lying to consumers :(
adrianN 7y ago
If the performance is alright for my needs, why wouldn't I prefer a processor with a lower TDP? I agree that it would be nice to have consumption numbers for some standardized workload, but in the absence of that, TDP seems useful to me.
- pingyong 7y ago
  >If the performance is alright for my needs, why wouldn't I prefer a processor with a lower TDP? Because 1. a processor with a lower TDP doesn't necessarily actually use less power, at least not if your cooler can dissipate much more than the TDP, which it typically can. And 2. because you can simply limit the clock speeds of any higher TDP CPU to reach any TDP you want. If you want a 35 W 3900X or 9900K, just set the clocks to whatever you need to reach 35 W max power usage, and you're done. Of course the lower TDP parts are typically cheaper, so it makes more sense to buy those. But that's their differentiating factor, the price, not the TDP.
  - Retric 7y ago
    TDP is very useful if you want a quiet PC without water cooling. Under clocking may be required based on case airflow, but you want someone to be making passive CPU coolers for your socket.
    - pingyong 7y ago
      Not sure what you're getting at, this is the same socket as all the other Ryzen 3000 CPUs... Not to mention that every slightly larger air cooler is a "passive cooler". Just don't connect the fan. Or set a fan curve that disables the fan as long as the CPU temperature is sub-62 C. Or 95 C, if you really don't want them to turn on.
      - Retric 7y ago
        Yes, in this specific case it not a big deal, and they make some surprisingly effective passive coolers today. However, I have run into this issue in the past. As to running a larger air cooler without a fan. That’s heavily dependent on case airflow. High speed case fans really defeat the purpose of a passive cooler.
Buraksr 7y ago
I think there is some merit to these chips having better power consumption. Generally the CCX's that draw more current under no cpu load are capable of higher clocks albeit at higher power draws at said clock.[i] That is to say is that the higher performance chips from the silicon lottery are the least efficent. So as you said, its "just a slightly worse binned version" but worse in terms of max clock not performance/watt. Although there isnt a 'hard' definition of TDP AMD has typically rated there chips more accurately[ii] than intel in the past [0], but that said AMD's TDP is still lower than absolute max power draw. [i]- Memories from working in validation, although this was not focus of my work, this is what I recall on the topic. [ii]- from amd's data sheet "The maximum power a processor draws for a thermally significant period while running commercially useful software. The constraining conditions for TDP are specified in the notes in the thermal and power tables." NOTE! This source is old!! [0]-https://www.anandtech.com/show/2807/2 https://www.anandtech.com/show/2807/2
- pingyong 7y ago
  >That is to say is that the higher performance chips from the silicon lottery are the least efficent. That is wrong generally. Not sure how you got that idea either. The chips that overclock the highest are typically the most efficient ones, too. A 9900K that can run at 5.3 GHz at 1.35v is going to use less power than a 9900K that needs 1.5v to run at 5.3 GHz. At any frequency. Because the "golden" chip simply leaks less power, and needs less voltage at any given frequency. Lower TDP parts aren't special in any way, they just have lower clocks. If you limit the clocks on higher TDP parts, you get the same (or better) power consumption.
  - Buraksr 7y ago
    The thing is they are the least efficent at idle. If you are seeing higher baseline current you can interpret this as the chip sort of having a lower internal resistance which is a double edge sword.
    - pingyong 7y ago
      If that difference exists, I'd be very surprised if it was even measurable with normal methods. Since on modern x86 CPUs most of the chip is literally just dead / not doing anything at idle. But feel free to surprise me in case someone actually tried that.
nguoi 7y ago
I'm impressed that it's only slightly higher than 1/3rd of the 2920X's TDP for the same number of similar cores. That doesn't feel like a normal jump whether it's massaged by marketing or not.
NicoJuicy 7y ago
Intel will for sure look like a hawk on the numbers that AMD claims. I don't think they will gain any advantage with lying.
beatgammit 7y ago
Why can't we just get a range? I care about TDP so I can estimate total power draw for my system when designing a custom build. I need to know about how big the PSU and UPS need to be, and getting a rough idea of electricity costs may influence my choices of components. I can't trust the TDP figures and instead need to look up actual tests to know what it really draws, which is unnecessarily complicated.
- cuu508 7y ago
  Power consumption changes drastically depending on how many volts the motherboard feeds into the CPU. Different motherboards use different default values and different algorithms. And on top of that users can go in and tweak OC settings. The only honest TDP range they can give you would be: TDP between 10 and 300W. I have a 9700K (95W TDP). At idle, the entire system consumes 30W at the wall. When running Prime95, the entire system consumes 250W, and that's undervolted. The 95W number is utterly useless. If I had bought a 95W capable cooler, the system would throttle under load.

JamesMcMinn 7y ago

Intel measure the TDP based on the base clock, yes. However AMD seem to measure it based on what the CPU is likely to draw with boost clocks over a sustained period of time, so their TDP numbers are quite accurate.

pingyong 7y ago
The 3900X still uses ~140 W at full load with a 105 W TDP. And still just like Intel, if you limit the clock speeds you can make it use 105 W, 65 W, or 35 W at full load, just like with Intel chips. AMD calculates the TDP a bit differently, but nothing really changes fundamentally. All CPUs in a generation are essentially the same chip, TDP is completely irrelevant.
- jankotek 7y ago
  Not the same chip, quality differs, some units would require higher voltage for the same frequency. Some CPUs are more power efficient because they can take lover voltage.
  - pingyong 7y ago
    Yeah and those chips are typically the ones being sold as higher TDP chips.
- pizza234 7y ago
  For users who have a fixed TDP budget, there's a substantial difference. The AMD power calculation is not "bit different", it's Intel who is cheating big time. On a system with constrained power values, those who buy Intel will suffer a substantially higher hit than those who buy AMD.
  - pingyong 7y ago
    > For users who have a fixed TDP budget, there's a substantial difference. I really, really don't see how. Both TDPs have very little connection to how much power the chips actually pulls at full load. 105 to 140 isn't useful in any way. If it was 107, sure, but 140 is 1/3rd higher than "spec" (I write "spec" because TDP isn't supposed to tell you what the highest power draw possible is if your cooling can dissipate more than the TDP in the first place, people just somehow seem to use it that way). If you have a fixed TDP cooler, all you have to do is put that cooler on CPUs and see which ones will be faster. No looking at the specs required. If you have a fixed power consumption budget, but a better cooler, all you have to do is downclock until the CPU stays within that budget and then compare performance. Again, spec wasn't useful.
- JamesMcMinn 7y ago
  140W is considerably closer to the stated 105W TDP value of the 3900X than a "95W" 9900k which can easily pull down 180W. Whilst I agree that TDP shouldn't be taken as gospel, at least in AMDs case, it can be a useful approximation the amount of heat generated (and thus power draw). If you then compare the actual performance per watt, a 12 core CPU at 3.1 base / 4.2 boost pulling down approximately 65W is very impressive. Something similar from Intel (in terms of number of cores at even just the 3.1 base frequency) would likely have a TDP of at least 120W.
  - pingyong 7y ago
    >140W is considerably closer Closer, yes, but more useful? Both are off by a mile - not to mention that TDP isn't supposed to tell you a chip's maximum power consumption in the first place. It's supposed to tell you how good your cooler has to be to sustain base clocks / single core turbo, or in AMD's case, to sustain base clocks and some? boost clocks for a limited time. >If you then compare the actual performance per watt Performance per watt can certainly be interesting for many people. Performance per watt just isn't connected to TDP. The 3900X (105 W TDP) has higher performance per watt than the 9900K (95 W TDP). Probably at any frequency - although potentially the 3900X can't clock down as much. The 9900K can run Cinebench without a cooler after all (at least the 8700K can, so I'd suspect the 9900K can do that too), while the AMD processors can't. Also, the 3900 (65 W TDP) has the same performance per watt as the 3900X (105 W TDP), if you let them run at the same clock speeds.
    - juergbi 7y ago
      Ryzen SKUs with a 105W TDP have a power limit (PPT) of 142W at stock. 65W TDP SKUs have a power limit of 88W. I.e., while these CPUs are allowed to use more power than their TDP, it's limited to 35% above the TDP. This means that the advertised TDP is not just an arbitrary number they slap on the package.
      - pingyong 7y ago
        It's not an arbitrary number on Intel's CPUs either, it's just still not very useful. Or at least it's not useful as an indicator of some sort of technological progress. If you limit a 3900X to 3900 clock speeds and voltages, it's going to behave exactly the same.
rasz 7y ago
AMD used to do that until Zen 2. With new generation AMD joined intel in lying to consumers :(

adrianN 7y ago

If the performance is alright for my needs, why wouldn't I prefer a processor with a lower TDP? I agree that it would be nice to have consumption numbers for some standardized workload, but in the absence of that, TDP seems useful to me.

pingyong 7y ago
>If the performance is alright for my needs, why wouldn't I prefer a processor with a lower TDP? Because 1. a processor with a lower TDP doesn't necessarily actually use less power, at least not if your cooler can dissipate much more than the TDP, which it typically can. And 2. because you can simply limit the clock speeds of any higher TDP CPU to reach any TDP you want. If you want a 35 W 3900X or 9900K, just set the clocks to whatever you need to reach 35 W max power usage, and you're done. Of course the lower TDP parts are typically cheaper, so it makes more sense to buy those. But that's their differentiating factor, the price, not the TDP.
- Retric 7y ago
  TDP is very useful if you want a quiet PC without water cooling. Under clocking may be required based on case airflow, but you want someone to be making passive CPU coolers for your socket.
  - pingyong 7y ago
    Not sure what you're getting at, this is the same socket as all the other Ryzen 3000 CPUs... Not to mention that every slightly larger air cooler is a "passive cooler". Just don't connect the fan. Or set a fan curve that disables the fan as long as the CPU temperature is sub-62 C. Or 95 C, if you really don't want them to turn on.
    - Retric 7y ago
      Yes, in this specific case it not a big deal, and they make some surprisingly effective passive coolers today. However, I have run into this issue in the past. As to running a larger air cooler without a fan. That’s heavily dependent on case airflow. High speed case fans really defeat the purpose of a passive cooler.

Buraksr 7y ago

I think there is some merit to these chips having better power consumption. Generally the CCX's that draw more current under no cpu load are capable of higher clocks albeit at higher power draws at said clock.[i] That is to say is that the higher performance chips from the silicon lottery are the least efficent. So as you said, its "just a slightly worse binned version" but worse in terms of max clock not performance/watt. Although there isnt a 'hard' definition of TDP AMD has typically rated there chips more accurately[ii] than intel in the past [0], but that said AMD's TDP is still lower than absolute max power draw. [i]- Memories from working in validation, although this was not focus of my work, this is what I recall on the topic. [ii]- from amd's data sheet "The maximum power a processor draws for a thermally significant period while running commercially useful software. The constraining conditions for TDP are specified in the notes in the thermal and power tables." NOTE! This source is old!! [0]-https://www.anandtech.com/show/2807/2 https://www.anandtech.com/show/2807/2

pingyong 7y ago
>That is to say is that the higher performance chips from the silicon lottery are the least efficent. That is wrong generally. Not sure how you got that idea either. The chips that overclock the highest are typically the most efficient ones, too. A 9900K that can run at 5.3 GHz at 1.35v is going to use less power than a 9900K that needs 1.5v to run at 5.3 GHz. At any frequency. Because the "golden" chip simply leaks less power, and needs less voltage at any given frequency. Lower TDP parts aren't special in any way, they just have lower clocks. If you limit the clocks on higher TDP parts, you get the same (or better) power consumption.
- Buraksr 7y ago
  The thing is they are the least efficent at idle. If you are seeing higher baseline current you can interpret this as the chip sort of having a lower internal resistance which is a double edge sword.
  - pingyong 7y ago
    If that difference exists, I'd be very surprised if it was even measurable with normal methods. Since on modern x86 CPUs most of the chip is literally just dead / not doing anything at idle. But feel free to surprise me in case someone actually tried that.

nguoi 7y ago

I'm impressed that it's only slightly higher than 1/3rd of the 2920X's TDP for the same number of similar cores. That doesn't feel like a normal jump whether it's massaged by marketing or not.

NicoJuicy 7y ago

Intel will for sure look like a hawk on the numbers that AMD claims. I don't think they will gain any advantage with lying.

beatgammit 7y ago

Why can't we just get a range? I care about TDP so I can estimate total power draw for my system when designing a custom build. I need to know about how big the PSU and UPS need to be, and getting a rough idea of electricity costs may influence my choices of components. I can't trust the TDP figures and instead need to look up actual tests to know what it really draws, which is unnecessarily complicated.

cuu508 7y ago
Power consumption changes drastically depending on how many volts the motherboard feeds into the CPU. Different motherboards use different default values and different algorithms. And on top of that users can go in and tweak OC settings. The only honest TDP range they can give you would be: TDP between 10 and 300W. I have a 9700K (95W TDP). At idle, the entire system consumes 30W at the wall. When running Prime95, the entire system consumes 250W, and that's undervolted. The 95W number is utterly useless. If I had bought a 95W capable cooler, the system would throttle under load.