Thermal Throttling Console
A chip can burst far above the power it can hold forever — until the silicon heats up and it throttles to survive. Find the sustained power ceiling, how much performance throttling costs, and how long a burst lasts before the thermal cliff.
Requested power, cooling θ & ambient → throttle verdict.
Burst-vs-sustained console
At 1100W the steady junction would reach 113°C — past the 105°C limit — so the chip throttles to 1000W (91% of requested). A burst from 40°C runs full-speed for ~8.8s before the cliff.
The 1000W ceiling is the cooling's doing — (Tj,max − ambient) ÷ θ. Better cooling or cooler air raises it; thermal mass only lengthens the burst.
Raise the ceiling: size cooling in the Heat Sink Sizing and Junction Temperature consoles.
Why burst and sustained diverge
When the junction nears its limit, the chip cuts clocks and voltage to reduce power — trading performance for survival. It's a safety mechanism, but every throttle is performance you paid for and didn't get.
A chip can sustain a burst far above its steady-state ceiling — until the silicon heats up. Benchmarks that finish before the thermal mass saturates look great; sustained workloads hit the cliff and settle far lower.
A heavier heat capacity heats up more slowly, lengthening the burst before throttling — but it doesn't change the steady-state ceiling. It shifts when you throttle, not whether.
The power a chip can hold indefinitely is the temperature budget divided by the thermal resistance to ambient. Better cooling raises that ceiling directly — which is the whole point of liquid cooling for sustained AI loads.
The cliff at the end of the burst
Every modern processor has two performance levels: the one it shows you in a quick burst, and the one it can actually hold forever. The gap between them is thermal throttling, and it's why a benchmark that finishes in seconds can wildly overstate how a chip behaves under a real, sustained workload. Understanding that gap is the difference between a spec sheet and reality.
The sustained ceiling is simple and unforgiving: it's the temperature budget divided by the thermal resistance to ambient. That's the power at which the junction sits exactly at its limit in steady state — request more and the chip must throttle back to it. Crucially, that ceiling is set by the cooling and the ambient, not by the chip's nameplate power, which is why the same silicon sustains far more on a liquid cold plate than on air, and far less in a 40°C hot aisle than on a 25°C bench.
Bursts escape the ceiling temporarily because silicon and heatsinks have thermal mass — they take time to heat up. When a heavy load starts, the temperature climbs exponentially toward its steady-state value with a time constant equal to the thermal resistance times the heat capacity, and the chip runs at full power until that climb crosses the limit. A larger thermal mass lengthens the burst, but it does not raise the ceiling: it changes when you throttle, not whether. The heating curve in this console shows exactly that — full speed until the line meets the limit, then the cliff.
To run a sustained workload without throttling, the ceiling has to clear the workload's power, and the lever for that is cooling. Size it in the Heat Sink Sizing console, confirm the steady junction temperature in the Junction Temperature console, and set the power itself with the Power Budget console.
Trusted by Performance & Thermal Engineering Teams
“The burst-vs-sustained distinction with a real time-to-throttle is exactly what I use to explain why our benchmark numbers don't hold under sustained load. The sustained ceiling = budget ÷ resistance framing makes the cooling dependency undeniable. Heating curve matches our telemetry.”
“The 40°C-inlet preset is the one that bites us — a part fine on the bench throttles in the hot aisle, and this predicts it. Throttle factor as lost performance is the number product teams understand. Pairs perfectly with the junction-temperature and cooling tools.”
“Clean steady ceiling, throttle factor and first-order time-to-throttle. The thermal-mass-buys-time-not-capacity point is the one engineers miss. Would love multi-time-constant modeling, but for burst-vs-sustained intuition it's excellent.”
“I use it to justify liquid cooling for sustained AI loads — showing the air ceiling below the workload power, and liquid raising it above, in one screen. The exponential heating curve to the throttle point is a great teaching aid. Fast and accurate.”
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sustained ceiling = (Tj,max − ambient) ÷ θ · Tj(t) = T∞ − (T∞ − Tstart)·e^(−t/τ) · τ = θ × thermal mass · Last reviewed: 2026-06