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I think undervolting is good for the environment to lower the carbon footprint of CPUs. Some never multicore CPUs has TDP of +100W, it would probably be much be

by acd 6y ago

I think undervolting is good for the environment to lower the carbon footprint of CPUs. Some never multicore CPUs has TDP of +100W, it would probably be much better if we lowered the voltage and frequency for a small CPU performance hit. Thankful to the developers of the driver! "The dynamic power consumed by a CPU is approximately proportional to the CPU frequency, and to the square of the CPU voltage:" https://en.wikipedia.org/wiki/CPU_power_dissipation https://en.wikipedia.org/wiki/CPU_power_dissipation ps. You can also undervolt, lower frequency of AMD CPUs.

bserge 6y ago
Not on newer processors, at least Intel, due to TurboBoost. Undervolting lowers voltage, but the processor will now stay at higher clocks for a longer time, hitting the same TDP/power limits. You'd need to undervolt and either reduce Turbo Power Limit or cap the clocks at something lower.
- SomeoneFromCA 6y ago
  > Undervolting lowers voltage, but the processor will now stay at higher clocks for a longer time, hitting the same TDP/power limits. No,at the same power, but for shorter amount of time, because now it is able do a lot more work per unit of time. So no, you'll definitely use less energy, although dissipate same amount of power. Keeping in mind, that your will be idling 90% of time, if not more, your savings will be even bigger.
  - bserge 6y ago
    Yeah, definitely for normal workloads/usage. I'm talking only constant full core load, synthetic tests like Prime95, rendering, or even gaming.
    - SomeoneFromCA 6y ago
      Even in that case, if your CPU cooler can deal with dissipating all the power (without throttling), consumed by the CPU in both cases (normal and undervolted), you'll still use less energy when undervolted.
      - bserge 6y ago
        But only if it's operating at maximum frequency, i.e. if the clocks are the limiting factor. As long as it's only TDP limited, voltage going down means amperage/current will go up in order to hit the power limit.
- xxs 6y ago
  Power scales with voltage squared and linearly with freq. Turboboost allows for higher clocks but you'd be getting that with or without undervolting.
nspattak 6y ago
I haven't made any estimates to how much energy is wasted like this but I "feel" that it is negligible. Max power consumption will not change in power demanding cases as cpu will still throttle up to the TDP limits. I think it will only consume less power when idling but I think that this is in the range of Watts.

by acd 6y ago

bserge 6y ago

Not on newer processors, at least Intel, due to TurboBoost. Undervolting lowers voltage, but the processor will now stay at higher clocks for a longer time, hitting the same TDP/power limits. You'd need to undervolt and either reduce Turbo Power Limit or cap the clocks at something lower.

SomeoneFromCA 6y ago
> Undervolting lowers voltage, but the processor will now stay at higher clocks for a longer time, hitting the same TDP/power limits. No,at the same power, but for shorter amount of time, because now it is able do a lot more work per unit of time. So no, you'll definitely use less energy, although dissipate same amount of power. Keeping in mind, that your will be idling 90% of time, if not more, your savings will be even bigger.
- bserge 6y ago
  Yeah, definitely for normal workloads/usage. I'm talking only constant full core load, synthetic tests like Prime95, rendering, or even gaming.
  - SomeoneFromCA 6y ago
    Even in that case, if your CPU cooler can deal with dissipating all the power (without throttling), consumed by the CPU in both cases (normal and undervolted), you'll still use less energy when undervolted.
    - bserge 6y ago
      But only if it's operating at maximum frequency, i.e. if the clocks are the limiting factor. As long as it's only TDP limited, voltage going down means amperage/current will go up in order to hit the power limit.
xxs 6y ago
Power scales with voltage squared and linearly with freq. Turboboost allows for higher clocks but you'd be getting that with or without undervolting.

nspattak 6y ago

I haven't made any estimates to how much energy is wasted like this but I "feel" that it is negligible. Max power consumption will not change in power demanding cases as cpu will still throttle up to the TDP limits. I think it will only consume less power when idling but I think that this is in the range of Watts.