Per-core thermal throttle reportedly coming to next-gen Intel CPUs — Arrow Lake leverages Fast Throttle for enhanced overclocking

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Fast Throttle could help overclockers tune unlocked Arrow Lake processors at high temperatures.

Intel Core Ultra CPU
(Image credit: Intel)

Fast Throttle is a per-core thermal throttling solution that debuted on 13th Generation Raptor Lake processors, among the best CPUs. It provides an alternative (more performant) method of temperature-related throttling compared to TJMax. Jaykihn claims that Fast Throttle will also come to Intel's upcoming Arrow Lake processors.

Fast Throttle is a largely unknown but exciting thermal throttling feature that debuted on 13th Generation Raptor Lake CPUs. The thermal throttling mechanism uses a clock-controlling mechanism known as clock modulation to keep a CPU within its defined thermal limits. This is very different from more conventional thermal throttling mechanisms, such as TJMax, which manually overrides the chip's operating frequency (multiplier) and voltage or manipulates Intel's turbo-boosting algorithm to keep temperatures in check.

Clock modulation is a technique that turns the physical CPU clock on or off to change a chip's performance and power consumption. Clock modulation performs the same capabilities as frequency/voltage changes, but rather than slowing down or speeding up a CPU's clock speed, it turns off the clock altogether for a particular duration of time.

Fast Throttle utilizes clock modulation to provide more fine-grained frequency control over the processor in thermally limited situations. Its main highlight is that it provides per-core throttling adjustments, only throttling cores that are overheating.

The per-core thermal throttling application technically debuted with 13th Generation Raptor Lake processors, but Intel locked out any customization, making the feature relatively useless. But, starting with Raptor Lake Refresh, Intel exposed manual customization to users, making it useful for overclockers.

Thermal throttling isn't precisely what you want when overclocking. Still, Intel's latest hybrid CPUs run so hot that users often have to tweak their overclocks around thermal throttling to gain as much performance as possible. As a result, Fast Throttle provides one way of optimizing performance under thermally constrained situations.

Although Fast Throttle has not been proven to be decisively better than all other thermal throttling mechanisms, it is the only one that Intel supports per-core thermal throttling, which can be advantageous on high-core-count chips. Arrow Lake will be the third-generation CPU architecture to adopt Fast Throttle.

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Aaron Klotz
Aaron Klotz
Contributing Writer

Aaron Klotz is a contributing writer for Tom’s Hardware, covering news related to computer hardware such as CPUs, and graphics cards.

20 Comments Comment from the forums
  • King_V
    So, is this a sort of like PWM for CPU cores? It's either on at full speed or off?

    The cynic in me wonders if this is a way for Intel to advertise that they never throttle back block speeds.
    Reply
  • TerryLaze
    King_V said:
    So, is this a sort of like PWM for CPU cores? It's either on at full speed or off?

    The cynic in me wonders if this is a way for Intel to advertise that they never throttle back block speeds.
    What's a back block speed?!
    Also they would have to advertise that their CPUs just shut off basically, how is this going to be any good advertisement? At least low speeds are speeds, off is no speed at all.
    Reply
  • NinoPino
    Terrible article. Seems to be written from AI.
    Starting with the fact that the article says nothing new because (according to the content of the article) the described feature is already present (identical) in 14th gen processors.
    The fact that "Fast Throttle debuted on 13th Generation Raptor Lake processors" is repeated almost identical three times (as the readers cannot remember what they read some seconds ago).
    At the start of article you say "It provides an alternative (more performant) method of temperature-related throttling..." and you contradict this in the conclusion saying "...has not been proven to be decisively better than all other thermal throttling mechanisms".
    On the functional description of Fast Throttle, there are a lot of false affermations.
    You wrote "Clock modulation is a technique that turns the physical CPU clock on or off to change a chip's performance and power consumption.". The technique is "Fast Throttle" (not clock modulation) that through a "clock modulation" signal permit to turn on/off the clock of the single cores (not the CPU). The physical CPU clock is not affected at all.
    You wrote "Clock modulation performs the same capabilities as frequency/voltage changes". This is simply false as yourself say in the article.
    Reply
  • JRStern
    Yah I couldn't make any sense out of this either.
    How is it done? Little thermometers, or monitoring power consumption and assuming the temperature effects? If it "turns off the clock" for how long, is it going to hang the programs, what?
    Reply
  • thestryker
    From what I've gathered its just the method of thermal management that changes. Who knows whether or not it will end up being an advantage in practice with ARL.

    I'd highly recommend anyone curious read through this for more information on the current practicality: https://skatterbencher.com/2023/10/27/raptor-lake-refresh-fast-throttle/
    Reply
  • kjfatl
    This method of clock control makes a lot of sense in a system with multiple processor cores running at different effective speeds utilizing common resources such as cache. Based on the description I read in the article, the base clock used by a group of processors along with shared resources such as cache can run at a common rate. Power reduction is obtained by using clock enables per core. Instead or running a clock enable to each register in the design, the clock for the core is modified to have fewer edges, but the edges are all still synchronous with the common system clock. This is particularly useful if the processor nominally runs at a faster rate than the cache. Leaving out the details, it eliminates the need for most synchronization logic in the data path since everything is running from a common clock. It also allows for very fine grain speed reductions.
    Reply
  • abufrejoval
    My take on this is that Intel is simply copying what AMD is doing already and all this obfuscation is about not quite naming and shaming Intel for being a copycat in all these things like modular chips and extremely fine grained clock turbos that fluidly adapt to all manner of operating constraints.
    Reply
  • kjfatl
    abufrejoval said:
    My take on this is that Intel is simply copying what AMD is doing already and all this obfuscation is about not quite naming and shaming Intel for being a copycat in all these things like modular chips and extremely fine grained clock turbos that fluidly adapt to all manner of operating constraints.
    Reply
  • kjfatl
    I don't see this as a negative. What Intel is doing is "standard design practice". First you get an architecture to work, then you refine it. I wouldn't call this extremely fine grained but brute force and cheap. Extremely fine grained takes a lot more silicon. This will happen too when power is shut off to parts of a core based on the instruction being executed. It is highly likely that this is occurring as well. Both AMD, Intel and now NVIDIA play off each other and push the window.
    A couple of decades ago, Apple was about to go bankrupt. Steve Jobs approached Bill Gates and asked for a handout. His pitch was, "You(Microsoft) need us as competition or your product will get stale and someone else will take over the market. Bill Gates agreed and purchased a large sum of non-voting stock which kept Apple in business.
    Reply
  • abufrejoval
    kjfatl said:
    I don't see this as a negative. What Intel is doing is "standard design practice". First you get an architecture to work, then you refine it. I wouldn't call this extremely fine grained but brute force and cheap. Extremely fine grained takes a lot more silicon. This will happen too when power is shut off to parts of a core based on the instruction being executed. It is highly likely that this is occurring as well. Both AMD, Intel and now NVIDIA play off each other and push the window.
    A couple of decades ago, Apple was about to go bankrupt. Steve Jobs approached Bill Gates and asked for a handout. His pitch was, "You(Microsoft) need us as competition or your product will get stale and someone else will take over the market. Bill Gates agreed and purchased a large sum of non-voting stock which kept Apple in business.
    I fully agree, for the consumers it's a good thing that Intel is following AMD's lead here.

    Now, if only they could just say so publically then writers like Mr. Klotz (klutz in German), wouldn't get into such a bind in trying to explain that Intel is no longer doing their original type of throttling, but what AMD has been doing for years, while making it sound like they invented something new themselves.

    Clearly Intel wants writers to push a message, but also in a certain way, which results in writers not doing their very best.

    And I guess we'll have similar stories about how Lunar Lake is doing something fantastic and new, even if they are simply following the fruity cult there.

    Intel is no longer a leader but desperately wants to look like one, and above all, not risk looking as if they are actually behind.

    Mr. Klotz is paying the price for those gyriations and getting roasted for it.

    I guess it pays the rent...
    Reply