the amount of cooling you get is proportional to the difference of component temperature to ambient temperature. thats why modern chips are engineered to run much hotter.

Until Dust Puppy kills 'em

Hey, is there a cooling solution that sprays water on some sort of heat spreader and lets it evaporate? Kidding. Kinda. But actually, is that possible?

Heat pipes sort of do that naturally without any active "spraying". They contain a fluid that phase changes and carries heat away. Closed loop water coolers have the active flow of water you want for maximum effect. I don't think your idea would be an improvement on that.

That's essentially what vapor chamber coolers are. It's a sealed unit where the working fluid evaporates on the CPU end, absorbing a ton of heat, and then condenses on the other side, before going back to do the cycle again. Because the heat of vaporization is so large, these can move a lot more heat than ordinary heat sinks.

For both Intel/AMD 100C is now a target, not a limit.

And for the consumer, changing the computer every 2 years, because the processor died, is a limit, not a target. /s

> On the other hand IMO operating a CPU at 90-100C is just insane.

No it isn't, the manufacturer literally says it's normal! I think people who spend as much money on cooling setups as the chip are the insane ones.

My favorite story: I once put Linux on a big machine that had been running windows, and discovered dmesg was full of thermal throttling alerts. Turns out, the heatsink was not in contact with the CPU die because it had a nub that needed to occupy the same space as a little capacitor.

I'd been using that machine to play X-plane for over two years, and I never noticed. It was not meaningfully slower: the throttling events would only happen every ten or so seconds. I'm still using it today, although with the heatsink fixed :)

I have a garage machine with a ca. 2014 Haswell that's been running full tilt at 90C+ for a good bit of its life. It just won't die.

     I have a garage machine with a ca. 2014 Haswell 
     that's been running full tilt at 90C+ for a good 
     bit of its life. It just won't die.

First of all: that's awesome.

Second: what's it doing spending that much time "full-tilt?" Just curious. Sounds like something interesting.

Alas, nothing that interesting. It mined bitcoin for awhile, back when it was feasible to make practically useful quantities of it that way. Never profitably obviously.

Right now, I use it as a 200W space heater I can turn off and on via SSH, just running busyloops. It works well enough for a single car garage in California.

Temperatures like that have been fairly normal for a few generations now - both for Intel and AMD. It might look insane compared to what you were used to seeing a decade ago, but it's actually not that crazy.

First, the temperature sensors got a lot better. Previously you only had one sensor per core/cpu, and it was placed wherever there was space - nowadays it'll have dozens of sensors placed in the most likely hotspots. A decade ago a 70C temp meant that some parts of the CPU were closer to 90C, whereas nowadays a 90C temp means the hottest part is actually 90C.

Second, the better sensors allow more accurate tuning. While 100C might be totally fine, 120C is probably already going to cause serious damage. The problem here is that you can't just rely on a somewhat-distant sensor to always be a constant 20C below the peak value: it's also going to be lagging a bit. It might take a tenth of a second for that temp spike in the hotspot to reach the sensor, but in the time between the spike starting and the temp at the sensor raising enough to trigger a downthrottle you could've already caused serious damage. A decade ago that meant leaving some margin for safety, but these days they can just keep going right up to the limit.

It's also why overclocking simply isn't really a "thing" anymore. Previous CPUs had plenty of safety margin left for risk-takers to exploit, modern CPUs use up all that margin by automatically overclocking until it hits either a temperature limit or a power draw limit.

Exactly. Temperature measurements are a lot like available memory measurements in that regard. People wonder why the OS uses up all available memory, and it's because the OS knows that empty memory is useless, while memory used to cache disk is potentially useful (and can always be discarded when that memory is needed for something else). So, the persistent state of memory is always "full".

Similarly, processors convert thermal headroom to performance, until they run out of thermal headroom. So if you improve the cooling on a processor that has work to do (rather than sleeping), it will use up that cooling and perform better, rather than performing the same and running cooler.

(Mobile processors operate differently, since they need to maintain a much tighter thermal envelope to not burn the user. And processors can also target power levels rather than thermals. But when a processor is in its default "run as fast as possible" mode, its normal operating temperature will be close to the 100C limit.)

There's a side benefit to this as well, your cooling solution is more effective at 90C than it is at 40C, you know, highschool physics, deltaT and all that.

That also comes with the side effect that the transistors are leakier at high temperature, leading to higher power for the same performance as compared with operating at a lower temperature. This effect is significant: in mobile systems it can easily be the case that turning on a fan (or speeding it up) leads to a net decrease in power consumption because the power saved by making the chip less leaky is more than the power spent running the fan.

> People wonder why the OS uses up all available memory

This is really no excuse to have Windows eating 12GB of RAM with an Edge (with 2 static tabs), excel some antivirus and Teams running. This (12GB) is just sick.

The good news is: you do not understand how modern (last 30+ years) OS memory management works.

If you have free ram the OS will cache all the recently accessed things. It costs effectively zero to cache them when you access them, and it costs effectively zero to evict from the cache if you actually need the memory for "useful" work. And if the cached thing is useful in the mean time, you win because RAM is still orders of magnitude faster than SSD. None of the scenarios are a perf loss. The only scenarios are "win" or "no gain."

"But won't the next application I load, load faster if there is free RAM?"

If you are asking this question, please refer back to the previous concept -- "it costs effectively zero to evict from the cache if you actually need the memory for 'useful' work." This is where people typically get confused. They think it takes work to evict things from the cache, just like it would require work to remove frequently used objects from your physical desk if you needed to free up space.

Once you understand that the rest should fall into place.

> but it's actually not that crazy.

Unless you take reliability into account.

    It might look insane compared to what you were used 
    to seeing a decade ago, but it's actually not that crazy.

I'm comparing it to a mid-range system I built last year: an Intel i5-13400F with a $60 closed-loop cooler.

It doesn't go past 45C even during Prime95 runs using all cores. And the 120mm fans aren't exactly howling either.

    First, the temperature sensors got a lot better. Previously 
    you only had one sensor per core/cpu, and it was placed wherever 
    there was space - nowadays it'll have dozens of sensors placed 
    in the most likely hotspots.

That's awesome to know. Thanks for the explanation.