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.
