Boost clock
Boost clock is the highest frequency a CPU will reach opportunistically on a light thread count when thermal and power headroom allow.
Also known as turbo clock, turbo boost, max boost
Measured by SystemCheck
Part of the four-stage run: a 60-second sustained CPU load reporting throughput, decay and consistency; a memory stage reporting bandwidth and latency; a calibrated GPU raster load reporting frame time, pacing and decay; and a path tracer reporting samples per second. The paragraphs below say which metric carries this term.
Boost is opportunistic by design. The processor continuously evaluates temperature, package power, current draw, and how many cores are active, then raises frequency as far as those constraints permit. The advertised boost clock is typically achievable on one or two cores, briefly, on a cool machine. It is a ceiling, not a promise.
This is why a spec sheet comparison between two CPUs on boost clock alone is close to worthless. A 5.8 GHz part that holds boost for four seconds before dropping to 4.6 GHz will lose to a 5.4 GHz part that holds 5.1 GHz indefinitely on anything longer than a menu transition. The interesting number is not how high it goes, but where it settles.
SystemCheck's CPU stage is built around exactly that distinction. It records throughput across the full 60-second load rather than sampling a peak, so the report separates early throughput from the level the machine actually settles at. A wide gap means your boost is short-lived; a narrow gap means your cooling and power delivery are keeping up.
Related terms