What is thermal throttling?
When a chip nears its top safe temperature, it slows down so it gets no hotter. That is thermal (heat) throttling. It protects the chip.
1. Near the limit, it slows down
Every chip has a top safe temperature (Tjmax), often about 100 °C. Near it, the chip lowers its clock speed and voltage (electrical push), like turning down a tap before a sink overflows.
2. Sensors watch the temperature
Tiny sensors across the chip measure its temperature many times every second. Unlike a sink's water level, the temperature is not the same everywhere, so the chip watches its hottest spot.
3. Fans first, shutdown last
As the chip warms, fans spin faster, like opening a sink's drain wider. If that is not enough, the chip slows down, and as a last step a safety switch (thermal trip) turns the power off.
4. A warning from the circuit board
Other parts can warn the chip too. If the power parts on its circuit board get too hot, a signal called PROCHOT (processor hot) makes it slow down immediately.
5. Safe, but at the right time
Slowing down when hot is a safety feature, not a bug. But slowing too early wastes speed, and slowing too late risks damage: both are bugs.
Words to know
- Sensor
- A tiny part that measures something, here the temperature.
- Tjmax
- The top safe temperature inside the chip, where the transistors are.
- Clock speed
- How fast the chip works, counted in ticks per second.
- Voltage
- The electrical push that drives the chip. Less push means less heat.
- Thermal trip
- A safety switch that turns the computer off when it is far too hot.
- PROCHOT
- Processor hot: a signal that tells the chip to slow down immediately.
- Board
- The main circuit board that holds the chip.
Where you meet it at work
Testers keep the chip fully busy until it heats up. They check that it slows at the right temperature and speeds up again once it cools.
Check yourself
Is thermal throttling a bug?Think first, then tap to see the answer.
No, it is a safety feature. Throttling too early or too late is a bug.