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No worries – I was carefully monitoring the CPU temperature with my finger.

That was a bit cringeworthy as someone who remembers the old TomsHardware video, and knows how rapidly new CPUs can change temperature/power consumption. You might end up with a damaged CPU, finger, or both. The amount of thermal mass relative to the power dissipation is tiny, and the BIOS definitely isn't going to put the CPU in power-saving mode right out of reset. I strongly recommend never powering on a "bare CPU" without a heatsink on it for anything newer than a (original) Pentium. Not having a working fan on the heatsink is not as bad, since the heatsink has plenty of thermal mass.

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I disagree. This seems to me to be the heart of tinkering. We don't always have the tools we need so sometimes improvise and especially since it was a cheap board and he knew the risks it seems perfectly fine to me. If everything needed to be perfect every time a lot of things would never happen. I smiled at that part of the story.

He had a heatsink; just didn't bother to put it on:

Success! I cleaned off the CPU with alcohol because I had been touching it, and fully installed the heatsink/fan.

Author here — maybe it was dumb of me to try, but it didn’t come close to a bad temperature. I get the feeling that the BIOS doesn’t stress the CPU very much. Of course, I would never try to boot an OS or let it sit for much longer than I did.

It's hard to imagine it using SMP, so only one core should be active, and it's not likely to use many of the advanced functional units. I imagine you have a pretty high "thermal margin" in that run state.

The fact that it had a heatspreader probably made the heating much less rapid than it could've been with a bare-die CPU like an old Athlon or some of the mobile ones.

Modern CPUs will throttle or halt long before they fry themselves.

They have throttling, and the newer ones are definitely "thermally governed", but without a heatsink to provide thermal mass, I'm not sure if they can react quickly enough to stop going over the limits. That said, a CPU with a heatspreader will have more mass than a bare die.

I repaired a piece of manufacturing equipment in 2018. It was terribly slow, even more so than one would expect from a first gen core i3. The heatsink had spent 8 years, hovering a few millimeters above the cpu. The Intel thermal paste was untouched.

I still remember a GeForce MX440 I bought once. It was stuttering as hell in games. Overclocked it for better performance. Still stuttering.

Looked at it and two of the plastic clips (yeap, no screws back then lol) holding the heatsink+fan were snapped so the heatsink wasn't even touching the die... WTF!

That was pretty hilarious. It worked fine for years after I fixed it, long enough for caps to blow and be replaced.

Basically, they're fucking sturdy.

To add on your anecdata: I've seen an MX440 with a fan glued to the die. Without a heatsink and I don't think that was a thermal glue. It worked badly, but it didn't die.

What is "quickly enough"?

Isn't the reaction time today somewhere on the order of a few milliseconds? How much could a component overheat in that time? The maximum current, though high, is still limited, after all.

Also, there is "thermally governed", and there is that hard reset once a critical temperature has been reached. I'm admittedly ignorant, but a "extremely short reaction time" with regards to a critical event seems like something that one could reasonably expect.

"I static'ed my component X" is something one hears frequently, but I don't think I've ever read about anyone frying their CPU anytime in the last decade.

Edit: Looking at a somewhat recent paper [1] studying CPU frequency transition latency, even the highest latencies were still within 70µs(!). I think one could reasonably expect a similar or better latency regarding critical protection circuitry.

[1] https://www.cse.iitd.ac.in/~sbansal/col862-lpc/ftalat.pdf

My experience is mostly with Intel mobile CPUs, which are mounted as bare die without a heatspreader, and those can jump 20-30C a second even in normal operation with a heatsink attached.

Sure, but that "second" you mention is an eternity compared to the max 30µs (see referenced paper) it takes a CPU to switch from highest to lowest frequency.

Why would you expect critical temperature threshold shutdown latency to take any longer?

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