The Sustained Performance Gap: Why Laptop Boost Clocks Don't Hold

Advertised boost clocks like 5.0 GHz are real, but they last seconds to minutes, not the duration of a render or gaming session. Under sustained load, once silicon approaches TjMax, firmware pulls back voltage and frequency to protect the chip — often cutting sustained speed 30-40% below peak.

Temperature isn't the only ceiling: Intel's PL1/PL2 power limits and AMD's equivalent power management framework can cap performance well before thermal limits are reached, independent of cooling headroom. Similarly, mobile GPUs like the RTX 4070 ship with Total Graphics Power configured anywhere from 35W to 115W by the OEM, meaning identically-branded chips can differ 30-50% in real-world performance.

For engineers and buyers, the practical takeaway is that chassis design, power budgeting, and shared CPU/GPU thermal infrastructure matter more than the model name on the spec sheet — two laptops with the 'same' silicon can behave very differently under sustained load.