Overview
Junction temperature is the temperature at the 'heart' of the chip, where the transistors are located. It is always higher than the temperature of the chip's casing or the heatsink.
Limits
Most silicon-based chips have a maximum rated junction temperature (TjMax) of around 100°C to 105°C. Exceeding this limit can lead to:
- Thermal Throttling: The chip slows itself down to reduce heat.
- Emergency Shutdown: The system turns off to prevent permanent damage.
- Reduced Lifespan: Long-term operation near the limit can degrade the silicon.
Monitoring
Modern CPUs and GPUs have multiple internal sensors to monitor junction temperature in real-time.