8 ms·

The whole point is that the CPU is only a single part of the equation. Yes, you're not going to burn out the CPU itself by unlimiting PL1/2 (although if the sys

by mjg59 4y ago

The whole point is that the CPU is only a single part of the equation. Yes, you're not going to burn out the CPU itself by unlimiting PL1/2 (although if the system vendor cheaped out on power circuitry because they'd only designed for sustained 20W draw then you might burn that out), but you're now generating more heat than the system is designed to dissipate. This may result in obvious outcomes like the chassis heating up enough to burn your legs, but it may also result in other components being operated outside their thermal limits and their lifetime being shortened as a result.

userbinator 4y ago
The experience of many users shows otherwise --- ThrottleStop has similar scary disclaimers, but I have yet to see any evidence of hardware damage caused by opening up the power limits and letting the CPU naturally attain its full performance. but you're now generating more heat than the system is designed to dissipate I believe that's more accurately rephrased as "now you have more performance than they wanted you to have", because that's how it's being used in practice. FYI, it is painfully obvious that you're toeing some sort of company line here. Edit: and getting flagged for pointing out the truth should itself be quite telling. ;-)
- mjg59 4y ago
  > "now you have more performance than they wanted you to have" "An unthrottled CPU without any OS-level policy will generate enough heat that the case temperature may rise to levels that violate safety regulations" can certainly be interpreted as "now you have more performance than they wanted you to have", yes. > FYI, it is painfully obvious that you're toeing some sort of company line here. I work for a company that develops trucks. While thermal dissipation is something that we do need to worry about, I can promise that it is absolutely not at the scale involved here. I've also been pretty consistent in criticising Intel for refusing to document DPTF. Whose company line do you think I'm toeing here?
  - userbinator 4y ago
    "An unthrottled CPU without any OS-level policy will generate enough heat that the case temperature may rise to levels that violate safety regulations" can certainly be interpreted as "now you have more performance than they wanted you to have", yes. Despite literally zero evidence of that actually being a problem in practice? I've also been pretty consistent in criticising Intel for refusing to document DPTF. Whose company line do you think I'm toeing here? Not Intel, but there's plenty of evidence that DPTF just cripples performance; and why else would you jump in to an article about unlocking manufacturer-crippled products with FUD like "not the correct approach"? It's like posting "may cause processor damage" and advocating for stock speeds on every article about overclocking. For the record, I've been overclocking (not at extreme or competitive levels) since the early 90s and haven't killed any hardware because of it. The system I'm posting this from has been on a 50% overclock for over a decade and it's still rock-solid stable.
    - dannyobrien 4y ago
      Not Intel, but there's plenty of evidence that DPTF just cripples performance; and why else would you jump in to an article about unlocking manufacturer-crippled products with FUD like "not the correct approach"? Seems like there are quite a few other reasons why someone would "jump in", including being a relative expert. Maybe you could think of a few others yourself?
    - mjg59 4y ago
      > Despite literally zero evidence of that actually being a problem in practice? Sustained contact with metal at a temperature as low as 45C is sufficient to cause discomfort, and it's a surprisingly small rise above that before you can actually cause burns (https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=31f3cd71a5e5dc229156fe52457af2bfb59f69d0 https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&d...). Skin temperature is a standard input to DPTF policies, and during my testing I was certainly able to get the skin temperature of my test laptop well above that level - DPTF would trigger throttling instead. > why else would you jump in to an article about unlocking manufacturer-crippled products with FUD like "not the correct approach"? DPTF defaults to a "safe" configuration, where "safe" is a euphemism for "almost unusably slow". If what you care about is your laptop not being almost unusably slow, it's reasonable to choose an approach that obtains that without introducing any additional thermal concerns. If what you care about is obtaining the absolute maximum performance possible from your hardware with no regard to any safety or longevity concerns, then yes, implementing the DPTF policy is probably not what you want to do. But recommending the latter without providing any information about the tradeoffs is irresponsible.
- Retric 4y ago
  Slap enough cooling on a CPU and it’s never going to thermal throttle. They added thermal throttling because most users only max out their CPU a tiny fraction of the time so the thermal inertia can compensate for inadequate cooling. It’s infrequent enough that most users could even disable it without noticing a difference. The problem is under the wrong conditions Aka inadequate cooling plus high ambient temperatures plus extreme workload = dead CPU. And no this isn’t theoretical, one summer working without AC I cooked a CPU before they added thermal protection. It actually happened to several people in the same heatwave.
  - jeffbee 4y ago
    Closed-loop thermal management a.k.a. "throttling" was an inevitable consequence of the invention of SpeedStep.
    - Retric 4y ago
      I recall 3 different stages, thermal protection was first designed to save chips if the cooling fans failed etc. It was very conservative because the only option was to turn the system off. SpeedStep was designed to save laptop battery life, so they never needed to thermal throttle in normal operation. Only fairly recently with Turbo Boost did Intel combine both ideas. It’s actually a fairly clever optimization as single threaded workloads benefit quite a bit from the extra thermal overhead.
      - jeffbee 4y ago
        The Pentium III was the last Intel CPU where shutdown was the only possible response to overheating, when the CPU asserted THERMTRIP#. The Pentium 4 has bidirectional PROCHOT# and the Thermal Control Circuit, which divides the clock down whenever the processor is hot, and continues to run.
        Retric 4y ago
        I had forgotten about P4 style thermal protection, but that wasn’t supposed to trip in normal operation the way SpeedStep and Turbo Boost is.

by mjg59 4y ago

userbinator 4y ago

The experience of many users shows otherwise --- ThrottleStop has similar scary disclaimers, but I have yet to see any evidence of hardware damage caused by opening up the power limits and letting the CPU naturally attain its full performance. but you're now generating more heat than the system is designed to dissipate I believe that's more accurately rephrased as "now you have more performance than they wanted you to have", because that's how it's being used in practice. FYI, it is painfully obvious that you're toeing some sort of company line here. Edit: and getting flagged for pointing out the truth should itself be quite telling. ;-)

mjg59 4y ago
> "now you have more performance than they wanted you to have" "An unthrottled CPU without any OS-level policy will generate enough heat that the case temperature may rise to levels that violate safety regulations" can certainly be interpreted as "now you have more performance than they wanted you to have", yes. > FYI, it is painfully obvious that you're toeing some sort of company line here. I work for a company that develops trucks. While thermal dissipation is something that we do need to worry about, I can promise that it is absolutely not at the scale involved here. I've also been pretty consistent in criticising Intel for refusing to document DPTF. Whose company line do you think I'm toeing here?
- userbinator 4y ago
  "An unthrottled CPU without any OS-level policy will generate enough heat that the case temperature may rise to levels that violate safety regulations" can certainly be interpreted as "now you have more performance than they wanted you to have", yes. Despite literally zero evidence of that actually being a problem in practice? I've also been pretty consistent in criticising Intel for refusing to document DPTF. Whose company line do you think I'm toeing here? Not Intel, but there's plenty of evidence that DPTF just cripples performance; and why else would you jump in to an article about unlocking manufacturer-crippled products with FUD like "not the correct approach"? It's like posting "may cause processor damage" and advocating for stock speeds on every article about overclocking. For the record, I've been overclocking (not at extreme or competitive levels) since the early 90s and haven't killed any hardware because of it. The system I'm posting this from has been on a 50% overclock for over a decade and it's still rock-solid stable.
  - dannyobrien 4y ago
    Not Intel, but there's plenty of evidence that DPTF just cripples performance; and why else would you jump in to an article about unlocking manufacturer-crippled products with FUD like "not the correct approach"? Seems like there are quite a few other reasons why someone would "jump in", including being a relative expert. Maybe you could think of a few others yourself?
  - mjg59 4y ago
    > Despite literally zero evidence of that actually being a problem in practice? Sustained contact with metal at a temperature as low as 45C is sufficient to cause discomfort, and it's a surprisingly small rise above that before you can actually cause burns (https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=31f3cd71a5e5dc229156fe52457af2bfb59f69d0 https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&d...). Skin temperature is a standard input to DPTF policies, and during my testing I was certainly able to get the skin temperature of my test laptop well above that level - DPTF would trigger throttling instead. > why else would you jump in to an article about unlocking manufacturer-crippled products with FUD like "not the correct approach"? DPTF defaults to a "safe" configuration, where "safe" is a euphemism for "almost unusably slow". If what you care about is your laptop not being almost unusably slow, it's reasonable to choose an approach that obtains that without introducing any additional thermal concerns. If what you care about is obtaining the absolute maximum performance possible from your hardware with no regard to any safety or longevity concerns, then yes, implementing the DPTF policy is probably not what you want to do. But recommending the latter without providing any information about the tradeoffs is irresponsible.
Retric 4y ago
Slap enough cooling on a CPU and it’s never going to thermal throttle. They added thermal throttling because most users only max out their CPU a tiny fraction of the time so the thermal inertia can compensate for inadequate cooling. It’s infrequent enough that most users could even disable it without noticing a difference. The problem is under the wrong conditions Aka inadequate cooling plus high ambient temperatures plus extreme workload = dead CPU. And no this isn’t theoretical, one summer working without AC I cooked a CPU before they added thermal protection. It actually happened to several people in the same heatwave.
- jeffbee 4y ago
  Closed-loop thermal management a.k.a. "throttling" was an inevitable consequence of the invention of SpeedStep.
  - Retric 4y ago
    I recall 3 different stages, thermal protection was first designed to save chips if the cooling fans failed etc. It was very conservative because the only option was to turn the system off. SpeedStep was designed to save laptop battery life, so they never needed to thermal throttle in normal operation. Only fairly recently with Turbo Boost did Intel combine both ideas. It’s actually a fairly clever optimization as single threaded workloads benefit quite a bit from the extra thermal overhead.
    - jeffbee 4y ago
      The Pentium III was the last Intel CPU where shutdown was the only possible response to overheating, when the CPU asserted THERMTRIP#. The Pentium 4 has bidirectional PROCHOT# and the Thermal Control Circuit, which divides the clock down whenever the processor is hot, and continues to run.
      - Retric 4y ago
        I had forgotten about P4 style thermal protection, but that wasn’t supposed to trip in normal operation the way SpeedStep and Turbo Boost is.