Editorial Boostgate: AMD’s Boost Clock Controversy

Boostgate: AMD’s Boost Clock Controversy

Boost Clocks: A Brief History

As is the case with any modern CPU, the clock speeds set by the manufacturer aren’t fixed. Using the Ryzen 7 3700X as an example, it has a base clock of 3600MHz. A base clock is the minimum frequency this model of CPU will perform at provided its thermal conditions are within a normal range. A normal range being the type of temperatures you would typically find in-home or office.

In contrast, a boost clock is the maximum clock frequency established by the manufacturer which is achievable under specific circumstances. For our Ryzen 7 3700X example, this would be 4.4GHz. In other words, boost clocks are factory overclocks set by the manufacturer of the CPU. These increases in clock speeds are the maximum speed obtainable on a single-core of the CPU in single-threaded or lightly threaded applications. These clocks never have been guaranteed under any circumstances, but generally speaking, these are easily reached on Intel and AMD’s previous generations of CPU’s. This history of easily achieving the manufacturer provided overclocks has created the perception that these clocks are something you should see while playing games or running applications which do not benefit heavily from multi-threading.

In the past, boost clocks have been achievable on any given CPU core on an Intel processor. When manually overclocking these CPU’s, it’s almost always possible to overclock all the CPU cores to the maximum boost clock speed. Using a Core i9 9900K as an example, it has a base clock of 3.6GHz like many AMD CPU’s. It has a boost clock of 5.0GHz. All of these CPU’s can achieve an all-core overclock of 5.0GHz outside of AVX workloads. If you go back nearly a decade, the Core i5 2500K could reach a clock speed of 5.0GHz on all four of its cores. Thus, we have nearly 10 years of this type of behavior to draw on.

Boosting

Intel has sold vast quantities of CPU’s equipped with its Turbo Boost feature which dwarf AMD’s sales. While Ryzen has occasionally outsold Intel’s offerings in a given price point, Intel’s Turbo Boost feature has been available for several years now and thus makes up the bulk of what the general public has experienced when it comes to boost clocks. AMD’s Ryzen 1000 and 2000 series CPU’s have boost clocks as well.

In contrast to Intel, AMD CPUs have a boost clock which outstrips what its CPU’s can do in an all-core overclock. For example, a Threadripper 2920X has a maximum boost clock of 4.3GHz, but typically an all-core overclock would only yield a result of 4.2GHz. For gaming and single-threaded applications, this meant that leaving the processor alone to run as AMD intended was generally the way to go. You could also extend the aggressiveness of the automatic overclocking using Precision Boost Overdrive, to great effect.

So, while AMD’s CPU’s behaved a little differently, the all-core overclock was very close to that of the maximum boost clock and most people were fine with this and seemed to know this in advance. Most all Ryzen CPU’s hit the same wall in a given product family. 4.0GHz-4.1GHz for the 1000 series, 4.1GHz-4.2GHz for the Ryzen 2000 series. AMD’s Threadripper CPU’s were said to get the top 5% of all Ryzen dies, and as a result, it achieved the upper range of the frequency wall more consistently, but rarely if ever went over.

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