Power limit (TDP)
Also searched as: power limit · tdp · thermal design power · wattage limit · power target
What it means
A power limit (often called TDP) is the wattage budget a CPU or GPU is allowed to draw. Hit the ceiling and the chip pulls its clocks back to stay inside it — even when it is running cool.
More detail
Modern chips boost their clocks as high as the power and temperature budgets allow, then back off when they reach either ceiling. The power limit is the wattage one: a GPU rated for, say, 250 watts lowers its clocks once it is pulling that much, which caps sustained performance regardless of temperature. It is why two cards with the same chip but different power limits perform differently, and why a laptop on a low-power profile feels slow even when it is cold. Raising the limit (where a vendor tool allows it) can let the chip hold higher clocks — at the cost of more heat, noise, and power draw — while LOWERING it trades a little performance for a much cooler, quieter machine. It is a different ceiling from heat: a chip can be power-limited while running cool, or thermal-throttling while well under its power budget.
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