5 ms·

The article's title says "at 35W", but the article text says "the T-series chip is rated at up to 106 Watts". That appears to refer to the chip's short-term tur

The article's title says "at 35W", but the article text says "the T-series chip is rated at up to 106 Watts". That appears to refer to the chip's short-term turbo power limit (PL2 in Intel parlance), typically effective for a default of 28 seconds if thermal limits don't kick in—but the time parameter can be adjusted by the end user (and this benchmark run has unknown provenance, so who knows what power management settings were in effect). Since the benchmark in question (Geekbench 5) only runs for a minute or two, it does most of its work before the chip even attempts to throttle down to anywhere near 35W. An actual power measurement averaged over the entire benchmark run would yield a significantly higher value than 35W.

mise_en_place 4y ago
I always get confused with Intel’s clock speeds and power draw now. Because depending on the p-state or c-state it’s in, it can be severely underclocked. Even trying to set “performance” p-state doesn’t work all the time, at least on my Ice Lake Xeon.
htk 4y ago
That's disappointing, I thought they were closer to Apple Silicon's performance/watt ratio. The deceptive nature of such benchmarks is also troubling.
- runnerup 4y ago
  The benchmarks themselves aren't really deceptive, but wccftech's reporting on them is misleading. These aren't claims being made by Intel, but just random user benchmarks that appeared online. For all benchmarks, context matters. These days, most in-depth reviewers understand how to work with transient power and thermal limits with respect to time. For example, measuring the MacBook Air M1's peak speed/time vs. its lower sustained speed after it hits thermal throttling around the 5-7 minute mark.
- toast0 4y ago
  It's kind of hard to compare performance/watt meaningfully when the wattages aren't at all similar. If you limit power on current generation Intel/AMD processors, the perf/watt is pretty good; depending on the specific load, sometimes better, sometimes worse than M2. When you allow more watts, perf goes up, but perf/watt goes down as you see diminishing returns. (With some loads, you may also have a point where more watts reduces performance, whoops) Geekbench isn't great as it doesn't even attempt to capture power usage, but that may not be available or accurate on all systems anyway.
deleted 4y ago
[deleted]
bee_rider 4y ago
It is a shame these kind of knobs are rarely exposed on a laptop. Sometimes I throttle my laptop cpu down to like 800MHz-1.2GHz to save power/prevent the fan from going. But this makes Vim less responsive for certain events. What I’d actually like is normal behavior but with the turbo clock limited to like… I dunno, a second.
- MikusR 4y ago
  https://www.techpowerup.com/download/techpowerup-throttlestop/ https://www.techpowerup.com/download/techpowerup-throttlesto...
- jeffbee 4y ago
  In Linux you want powercap tools. You can tune all three parameters in terms of power and time constant, so you can do exactly what you suggest. You can change it on the fly without rebooting so you could have a ridiculous setup like mine where I have the power limits wired up to two unused buttons on my mouse.
  - bee_rider 4y ago
    Cunningham’d. Awesome, I’ll look into it, thanks.
    - bee_rider 4y ago
      Seems to work pretty well. I was initially confused — it seems the default on my system had the “long term” limit set to some very high value, which made my changes to the short term moot. Seems like an odd default but I’ll blame ASUS for that I guess. Still slightly confused as to what exactly the “time window” means physically. With mine set to 1000us I still seem to get multiple seconds at full power. But it bumps down before the fan spins up so that seems good enough! Looking forward to the inevitable realization tomorrow that this is going to make my computer unusable in zoom calls.
- tambourine_man 4y ago
  If Vim isn’t responsive in a machine with hundreds of MHz something is very wrong with your setup. Vim was fast on machines with dozens of MHz. Either a bad terminal emulator or some plugin making it slow, I’d guess.
ajross 4y ago
> Since the benchmark in question (Geekbench 5) only runs for a minute or two, it does most of its work before the chip even attempts to throttle down to anywhere near 35W. That doesn't sound right at all. Nothing in a PC system (absent water systems with huge reservoirs I guess) is going to buffer excess heat on minute-long timescales, not even close. There's literally nowhere for that energy to go; 125W for a minute would be melting the solder joints. CPU throttling works on at most small-integer-second scales.
- wtallis 4y ago
  CPU throttling happens on many different timescales. That's why Intel processors have multiple power limits (PL1, PL2, PL3, PL4), in addition to current and temperature-based throttling mechanisms. The time constant for PL2 is usually either 28 seconds or 56 seconds. At those timescales, the concern is usually not with power delivery or CPU die temperature but rather with exterior case temperatures that the user may be directly touching. Based on the reported benchmark performance, it seems very unlikely that temperature-based throttling kicked in, and it's clear that the chip was operating well above 35W for at least a large portion of the benchmark run. So the PL1 and PL2 turbo power limits are the relevant controls at play here.
  - ajross 4y ago
    Yeah yeah, I know. I'm just saying that there's zero chance that throttling is affecting this measurement. The idea that an Intel machine is significantly faster for 2-3 minutes after the start of a benchmark is just silly, that's not the way these things work. Go start a benchmark of your own to see. Again, the thermodynamic argument is fundamental here. You're saying that a "35W" CPU is "actually" drawing power equivalent to a 125W CPU for exactly the time of a benchmark, which is several minutes. That excess would have nowhere to go! There's no reservoir to store it. (Obviously the cooling system could take it away, but part of your argument is that the cooling system is only good for 35W!).
    - wtallis 4y ago
      > The idea that an Intel machine is significantly faster for 2-3 minutes after the start of a benchmark is just silly, that's not the way these things work. Go start a benchmark of your own to see. I've done so, on many occasions, with actual power meters rather than trusting software power estimates. You really do commonly see a laptop's power consumption drop significantly ~28 seconds into a multithreaded CPU benchmark. > (Obviously the cooling system could take it away, but part of your argument is that the cooling system is only good for 35W!). I make no such claim that the cooling system is limited to 35W. I only claim that the default platform power management settings from Intel impose a 35W long-term power limit, unless the system builder has adjusted the defaults to account for whatever form factor and cooling choices they've made. Perhaps you haven't realized that the turbo power limits will still kick in even if the CPU die temperature is not too hot—because they're not actually a temperature-based control mechanism?

mise_en_place 4y ago

I always get confused with Intel’s clock speeds and power draw now. Because depending on the p-state or c-state it’s in, it can be severely underclocked. Even trying to set “performance” p-state doesn’t work all the time, at least on my Ice Lake Xeon.

htk 4y ago

That's disappointing, I thought they were closer to Apple Silicon's performance/watt ratio. The deceptive nature of such benchmarks is also troubling.

runnerup 4y ago
The benchmarks themselves aren't really deceptive, but wccftech's reporting on them is misleading. These aren't claims being made by Intel, but just random user benchmarks that appeared online. For all benchmarks, context matters. These days, most in-depth reviewers understand how to work with transient power and thermal limits with respect to time. For example, measuring the MacBook Air M1's peak speed/time vs. its lower sustained speed after it hits thermal throttling around the 5-7 minute mark.
toast0 4y ago
It's kind of hard to compare performance/watt meaningfully when the wattages aren't at all similar. If you limit power on current generation Intel/AMD processors, the perf/watt is pretty good; depending on the specific load, sometimes better, sometimes worse than M2. When you allow more watts, perf goes up, but perf/watt goes down as you see diminishing returns. (With some loads, you may also have a point where more watts reduces performance, whoops) Geekbench isn't great as it doesn't even attempt to capture power usage, but that may not be available or accurate on all systems anyway.

deleted 4y ago

[deleted]

bee_rider 4y ago

It is a shame these kind of knobs are rarely exposed on a laptop. Sometimes I throttle my laptop cpu down to like 800MHz-1.2GHz to save power/prevent the fan from going. But this makes Vim less responsive for certain events. What I’d actually like is normal behavior but with the turbo clock limited to like… I dunno, a second.

MikusR 4y ago
https://www.techpowerup.com/download/techpowerup-throttlestop/ https://www.techpowerup.com/download/techpowerup-throttlesto...
jeffbee 4y ago
In Linux you want powercap tools. You can tune all three parameters in terms of power and time constant, so you can do exactly what you suggest. You can change it on the fly without rebooting so you could have a ridiculous setup like mine where I have the power limits wired up to two unused buttons on my mouse.
- bee_rider 4y ago
  Cunningham’d. Awesome, I’ll look into it, thanks.
  - bee_rider 4y ago
    Seems to work pretty well. I was initially confused — it seems the default on my system had the “long term” limit set to some very high value, which made my changes to the short term moot. Seems like an odd default but I’ll blame ASUS for that I guess. Still slightly confused as to what exactly the “time window” means physically. With mine set to 1000us I still seem to get multiple seconds at full power. But it bumps down before the fan spins up so that seems good enough! Looking forward to the inevitable realization tomorrow that this is going to make my computer unusable in zoom calls.
tambourine_man 4y ago
If Vim isn’t responsive in a machine with hundreds of MHz something is very wrong with your setup. Vim was fast on machines with dozens of MHz. Either a bad terminal emulator or some plugin making it slow, I’d guess.

ajross 4y ago

> Since the benchmark in question (Geekbench 5) only runs for a minute or two, it does most of its work before the chip even attempts to throttle down to anywhere near 35W. That doesn't sound right at all. Nothing in a PC system (absent water systems with huge reservoirs I guess) is going to buffer excess heat on minute-long timescales, not even close. There's literally nowhere for that energy to go; 125W for a minute would be melting the solder joints. CPU throttling works on at most small-integer-second scales.

wtallis 4y ago
CPU throttling happens on many different timescales. That's why Intel processors have multiple power limits (PL1, PL2, PL3, PL4), in addition to current and temperature-based throttling mechanisms. The time constant for PL2 is usually either 28 seconds or 56 seconds. At those timescales, the concern is usually not with power delivery or CPU die temperature but rather with exterior case temperatures that the user may be directly touching. Based on the reported benchmark performance, it seems very unlikely that temperature-based throttling kicked in, and it's clear that the chip was operating well above 35W for at least a large portion of the benchmark run. So the PL1 and PL2 turbo power limits are the relevant controls at play here.
- ajross 4y ago
  Yeah yeah, I know. I'm just saying that there's zero chance that throttling is affecting this measurement. The idea that an Intel machine is significantly faster for 2-3 minutes after the start of a benchmark is just silly, that's not the way these things work. Go start a benchmark of your own to see. Again, the thermodynamic argument is fundamental here. You're saying that a "35W" CPU is "actually" drawing power equivalent to a 125W CPU for exactly the time of a benchmark, which is several minutes. That excess would have nowhere to go! There's no reservoir to store it. (Obviously the cooling system could take it away, but part of your argument is that the cooling system is only good for 35W!).
  - wtallis 4y ago
    > The idea that an Intel machine is significantly faster for 2-3 minutes after the start of a benchmark is just silly, that's not the way these things work. Go start a benchmark of your own to see. I've done so, on many occasions, with actual power meters rather than trusting software power estimates. You really do commonly see a laptop's power consumption drop significantly ~28 seconds into a multithreaded CPU benchmark. > (Obviously the cooling system could take it away, but part of your argument is that the cooling system is only good for 35W!). I make no such claim that the cooling system is limited to 35W. I only claim that the default platform power management settings from Intel impose a 35W long-term power limit, unless the system builder has adjusted the defaults to account for whatever form factor and cooling choices they've made. Perhaps you haven't realized that the turbo power limits will still kick in even if the CPU die temperature is not too hot—because they're not actually a temperature-based control mechanism?