5 ms·

Awesome work, and I'm glad you could post some results! I'm hoping to get time to delid one, put on a peltier cooler, and try to control the temperature a littl

Awesome work, and I'm glad you could post some results! I'm hoping to get time to delid one, put on a peltier cooler, and try to control the temperature a little better for a run to see how high it'll go before either burning up or going unstable. From my testing on clocks on the Pi 5, it looks like the default clock of 2.4 GHz is pretty close to the sweet spot for this chip (BCM2712), and you burn a lot of power for small incremental gains after that[1]. (Which you seem to also show with the 3.3 GHz overclock!). I also spoke to one of the Pi engineers about the chip behavior at higher clocks, and he suggested unlike some chips, this chip might run more stably at higher temperatures (like 50-60°C) rather than 'as cold as you can get it'. So that poses some challenges since most cooling solutions aren't tuned for 'keep a temperature' but instead 'get it as cold as possible', without a lot of manual tweaking. [1] https://www.jeffgeerling.com/blog/2023/overclocking-and-underclocking-raspberry-pi-5 https://www.jeffgeerling.com/blog/2023/overclocking-and-unde...

metadat 2y ago
Did the engineer explain why the higher temps contribute to stability? I've not heard of such a phenomenon before.
- geerlingguy 2y ago
  No physics-level explanation, just that they found the chips to be more stable in testing when they were a little warmer vs a little colder. The key was to keep them around that temperature, though, which still requires a good amount of cooling the more voltage that runs through it! Just... he mentioned I might not have as much success using LN2 or something more exotic, compared to standard water or Peltier cooling.
  - metadat 2y ago
    That's pretty crazy, thanks for sharing, Jeff. Overclocking was my bread and butter as a [relatively] broke teenager in the late nineties, around the era of the first Athlon Thunderbirds, when you could take a 1GHz chip and [maybe] OC it to 1.5Ghz. It was a great time to be alive, and yet this is the first case I've heard of where LN2 would not give you a dramatically better result 99.99%+ of the time! I still miss HardOCP and Kyle Bennett and his team's reviews. That one t-bird with char spots... It still worked reliably somehow, I might even have it in a box somewhere. Those swirly finned CPU coolers were shit! I came home every day after school and volted/burned the hell out of that poor chip, not realizing what I was doing.. lol.
    - K0balt 2y ago
      I still remember my dual celeron 450 clocked to 900 mhz. Those chips ran rock solid at double their rated clock, no didling the voltage or anything. Just needed decent cooling. Never mind that at the time having 2 processors was nearly useless.
      - geerlingguy 2y ago
        Heh, back in those days decent cooling was a lot easier than now (for overclocking, at least). That's one nice thing working on these little mobile chips—I don't need a $300 cooler, I can use a cheap little water block, or a small peltier element that doesn't cost much at all... and it's not being a space heater for the room. It's only pulling maybe 10-20W max.
        metadat 2y ago
        Where are these "cheap" water blocks you speak of? Haha, I've never encountered such a thing. Except maybe the $100 Corsair liquid coolers, but c'mon, they aren't real water cooling
      - riedel 2y ago
        I still remember that time, when you actually waited for the low end chip to be released and get it as fast as the earlier released flagships. Was a different time. But I also roughly remember having a dual socket board at the time with two overclocked celerons if my mind does not fool me. Funnily my wife is still using this 25 year old PC case, in which I glued bitumen for sound damping, for her current ryzen based PC.
        MattPalmer1086 2y ago
        Haha, yes, back in the 90s I had a dual Gigabyte motherboard and two 300Mhz Celerons overclocked to 450. Helped a lot with 3d animation and video rendering, but not much else!
      - bayindirh 2y ago
  - jonatron 2y ago
    I have extensive experience in watching LTT's jank cooling videos, and I think water cooling with a big relatively big reservoir would be able to keep the temperature at a chosen temperature. I found someone who has done it: https://www.youtube.com/watch?v=iBNSbzTzfSE&t=20s https://www.youtube.com/watch?v=iBNSbzTzfSE&t=20s using this kit: https://www.seeedstudio.com/High-Performance-Liquid-Cooler-for-Raspberry-Pi-5-p-5854.html https://www.seeedstudio.com/High-Performance-Liquid-Cooler-f...
  - nsteel 2y ago
    The temperature inversion effect is more pronounced at 16nm (Pi 5) than older nodes. This results in high VT cells performing better when warmer, the opposite of what we are used to. At the "normal" operating conditions (temp and frequency), this shouldn't be noticeable but when your at the absolute frequency limit it's not ideal for your critical path (where you normally use HVT cells) to get any slower. Perhaps it's related to this.
  - ZiiS 2y ago
    Wonder if it was more to do with deltas. Everything at 50° might be more stable then hotspots?
- deleted 2y ago
  [deleted]
c0balt 2y ago
This might be naive but you may take a look at warm water cooling from HPC/ Hyper Scalers. Combined with a custom block this should stay stable at the 50-60° sweet spot.
fl0ki 2y ago
> but instead 'get it as cold as possible' More like 'get it as ambient as possible' so if you're in a 50 degree room you're all set.
- trvz 2y ago
  You've mixed up Celsius and Fahrenheit.
  - fl0ki 2y ago
    I don't see where anybody in this thread or the linked article said Fahrenheit. Where do you see mixed units?
tonetegeatinst 2y ago
I find myself disappointed in the lack of helium cooled silicon chips in the modern year of 2024.

metadat 2y ago

Did the engineer explain why the higher temps contribute to stability? I've not heard of such a phenomenon before.

geerlingguy 2y ago
No physics-level explanation, just that they found the chips to be more stable in testing when they were a little warmer vs a little colder. The key was to keep them around that temperature, though, which still requires a good amount of cooling the more voltage that runs through it! Just... he mentioned I might not have as much success using LN2 or something more exotic, compared to standard water or Peltier cooling.
- metadat 2y ago
  That's pretty crazy, thanks for sharing, Jeff. Overclocking was my bread and butter as a [relatively] broke teenager in the late nineties, around the era of the first Athlon Thunderbirds, when you could take a 1GHz chip and [maybe] OC it to 1.5Ghz. It was a great time to be alive, and yet this is the first case I've heard of where LN2 would not give you a dramatically better result 99.99%+ of the time! I still miss HardOCP and Kyle Bennett and his team's reviews. That one t-bird with char spots... It still worked reliably somehow, I might even have it in a box somewhere. Those swirly finned CPU coolers were shit! I came home every day after school and volted/burned the hell out of that poor chip, not realizing what I was doing.. lol.
  - K0balt 2y ago
    I still remember my dual celeron 450 clocked to 900 mhz. Those chips ran rock solid at double their rated clock, no didling the voltage or anything. Just needed decent cooling. Never mind that at the time having 2 processors was nearly useless.
    - geerlingguy 2y ago
      Heh, back in those days decent cooling was a lot easier than now (for overclocking, at least). That's one nice thing working on these little mobile chips—I don't need a $300 cooler, I can use a cheap little water block, or a small peltier element that doesn't cost much at all... and it's not being a space heater for the room. It's only pulling maybe 10-20W max.
      - metadat 2y ago
        Where are these "cheap" water blocks you speak of? Haha, I've never encountered such a thing. Except maybe the $100 Corsair liquid coolers, but c'mon, they aren't real water cooling
    - riedel 2y ago
      I still remember that time, when you actually waited for the low end chip to be released and get it as fast as the earlier released flagships. Was a different time. But I also roughly remember having a dual socket board at the time with two overclocked celerons if my mind does not fool me. Funnily my wife is still using this 25 year old PC case, in which I glued bitumen for sound damping, for her current ryzen based PC.
      - MattPalmer1086 2y ago
        Haha, yes, back in the 90s I had a dual Gigabyte motherboard and two 300Mhz Celerons overclocked to 450. Helped a lot with 3d animation and video rendering, but not much else!
    - bayindirh 2y ago
- jonatron 2y ago
  I have extensive experience in watching LTT's jank cooling videos, and I think water cooling with a big relatively big reservoir would be able to keep the temperature at a chosen temperature. I found someone who has done it: https://www.youtube.com/watch?v=iBNSbzTzfSE&t=20s https://www.youtube.com/watch?v=iBNSbzTzfSE&t=20s using this kit: https://www.seeedstudio.com/High-Performance-Liquid-Cooler-for-Raspberry-Pi-5-p-5854.html https://www.seeedstudio.com/High-Performance-Liquid-Cooler-f...
- nsteel 2y ago
  The temperature inversion effect is more pronounced at 16nm (Pi 5) than older nodes. This results in high VT cells performing better when warmer, the opposite of what we are used to. At the "normal" operating conditions (temp and frequency), this shouldn't be noticeable but when your at the absolute frequency limit it's not ideal for your critical path (where you normally use HVT cells) to get any slower. Perhaps it's related to this.
- ZiiS 2y ago
  Wonder if it was more to do with deltas. Everything at 50° might be more stable then hotspots?
deleted 2y ago
[deleted]

c0balt 2y ago

This might be naive but you may take a look at warm water cooling from HPC/ Hyper Scalers. Combined with a custom block this should stay stable at the 50-60° sweet spot.

fl0ki 2y ago

> but instead 'get it as cold as possible' More like 'get it as ambient as possible' so if you're in a 50 degree room you're all set.

trvz 2y ago
You've mixed up Celsius and Fahrenheit.
- fl0ki 2y ago
  I don't see where anybody in this thread or the linked article said Fahrenheit. Where do you see mixed units?

tonetegeatinst 2y ago

I find myself disappointed in the lack of helium cooled silicon chips in the modern year of 2024.