A spec sheet lists parts and ceilings: core count, boost clock, memory size. A performance test measures what those parts deliver in the conditions you run them in.
- Two machines with the same processor can sustain different levels, because cooling, power settings and the chassis decide how long the ceiling can be held.
- SystemCheck reports measured throughput for each stage, with an interval, rather than reading a part name and looking up a number.
- A browser sees the logical processor count, and that can be capped; it does not see the exact model, the clock or the temperature.
The short answer
Specs describe the parts; a performance test describes the machine. The spec sheet tells you the maximum each part is allowed to do. A test runs real work and reports how much of it got done, second by second, which is the only way to see what a particular machine sustains.
What the spec sheet tells you
Core and thread counts tell you how much work can run at once. The boost clock is a ceiling the processor reaches when power, current and temperature allow, not a speed it holds. Memory size says how much fits before the system reaches for the drive; memory speed is a rating, and what you measure depends on how many channels are filled and how the system is set up.
What SystemCheck measures
Each stage reports measured work, not a looked-up figure.
- CPU: a floating-point WebAssembly kernel on every logical processor the browser reports, for 60 s in a Standard run, reported as a sustained level, a boost step and settled decay.
- Memory: copy bandwidth with one stream and with several, and latency from a dependent-load walk.
- GPU: a WebGL2 raster scene at a fixed render size for 50 s in a Standard run, then path tracing.
- Every figure carries a 95% interval, so two runs can be compared without reading noise as change.
When the numbers and the specs disagree
A figure lower than you expected from the specs is not proof of a fault. The browser, its power mode, battery power and background programs all sit between the hardware and the test. The report names the conditions it saw, such as battery power or a hidden tab. If the figures still look low on mains with nothing else running, compare with another run of the same mode before drawing a conclusion.
Terms used here
Questions
- Can SystemCheck read my exact processor and graphics card?
- No. Browsers report the logical processor count, which can be capped, and an approximate graphics renderer name that is increasingly masked. Your operating system's About page names the parts.
- Is a higher boost clock always faster?
- Only for as long as the machine can hold it. Over sustained work the cooling and power limits decide the level, which is why SystemCheck reports the settled level apart from the boost.