4 ms·

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 t

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.
    - rowanG077 7y ago
      Can you tell me the formula which will approximately give me the max TDP used by a recent Intel CPU based on its rated TDP?

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.
  - rowanG077 7y ago
    Can you tell me the formula which will approximately give me the max TDP used by a recent Intel CPU based on its rated TDP?