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Why do CPU’s throttle around 90c when silicon had a melting point of 1410c? What damage would be done to the CPU if you removed protections? (self.askscience)
submitted 8h ago by CockEyedBandit
Anton_Pannekoek 1 points 4h ago
The problem is that as it gets hot, the charge carrier mobility of silicon goes up, this causes leakage currents as the conductivity of silicon goes down. Then errors start occurring, and damage can even be caused.
Most CPUs will shut down when they get too hot.
Most CPUs will shut down when they get too hot.
jedp 1 points 2h ago
That's the main issue. However, something else to keep in mind is that an IC isn't just the silicon of its die. There's also the chip carrier which holds the die and provides connections, the epoxy coating which protects the die, and the solder which connects the legs or pads of the chip carrier to the system. All these things, and maybe more that I'm forgetting, have thermal limits. The solder, in particular, can be prone to failure because of repeated heating and cooling cycles.
Moff_Tigriss 1 points 47m ago
On that subject, Gamers Nexus did a phenomenal analysis of the thermal runaway early Ryzen 7000 suffered. Pictures normally never to be seen publicly, done by an enterprise specialized in hardware failure analysis.
https://www.youtube.com/watch?v=fFNi3YNJXbY
Basically, yeah, the moment epoxy outgasses, even extremely locally, the whole thing is breaking appart.
https://www.youtube.com/watch?v=fFNi3YNJXbY
Basically, yeah, the moment epoxy outgasses, even extremely locally, the whole thing is breaking appart.
speculatrix 1 points 1h ago
At what temperature does electromigration start to become an issue it's sustained for a long time?
MiffedMouse 1 points 1h ago
The doping ions (from PN doping that makes CMOS) that make the computer transistors function also become more mobile as the chip gets hotter, meaning hotter chips will fail sooner. That might not sound terrible, but keep in mind the heat from your chip is generated mostly in the CPU. By the time the thermometer is reading 90 C the transistors in the CPU are even hotter.
[deleted] 1 points 3h ago
[removed]
hydroracer8B 1 points 39m ago
What about all the plastics and other metals in the connections & circuit board? Those definitely melt at a much lower temp than silicon
These components don't operate in isolation - the whole system needs to stay intact in order to function
These components don't operate in isolation - the whole system needs to stay intact in order to function
Clancy3000 1 points 21m ago
Some have brought this up. But some people miss interpret a materials fundamental state change point (i.e. melting point, freezing points, etc) as the threshold for application practicality. Similar arguments were made during Sept. 11 (the ole jet fuel doesn't burn hot enough to melt steel) which is true but, steel doesn't need to reach its melting point to lose its load bearing structural integrity. Similar to silicon here - although silicons melting point is much higher than 90C it loses it ability to function as a semiconductor material at around those temperatures.
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