Last year Matt Dillon posted results on underclocking a Ryzen Threadripper system, particularly the memory, that focused on optimizing the total amount of electrical energy used to build a large software project. My recollection is that the results were interesting in that neither the highest nor lowest clock speeds achieved optimal efficiency, but some intermediate setting.Biero wrote: ↑Wed Aug 28, 2019 3:28 pmWell, I get your point about automatic underclocking. If I use the Pi 4 as desktop computer, I’ll probably let it manage its frequency.
But my first use will be media center. Currently I have a Pi 2 and it’s wonderfull : it’s switched on 24h a day, it’s always immediately available. And it does not generate heat which is a good thing as it’s inside a closed furniture => I like the idea that the temperature does not rise inside.
Going to a Pi 4 would add benefits (H265, USB powered Hard Drive, Gigabit…). But :
- Even in idle condition it seems that the heat is noticeable
- In use (nearly whatever usage), I saw lots of feed-back saying that the CPU reach 80°C quickly and stay there underclocking automatically.
So, I understand there is no damaging problem to fear. But also, if heat can be reduced in a media player usage switched on 24h a day (inside a closed furniture…), why not ? That’s why I thought in underclocking. It can be both at max and min speed by the way :
- arm_freq=1300 (instead of 1500) (In fact it could be less than 1300… I just want the Pi to handle H265 flow => If 1000 is OK, then perfect !)
- arm_freq_min = 400 (for example ? instead of 600 if I’m correct ?)
I hope you got my point for media player usage, switched on 24h a day, with minimum heat. Ideally I would need a Pi2 with H265 capability ! I understand there is no reliability problem with the Pi 4, but if it can be optimized in media player usage, it could be useful !
Maybe the people who designed it have already optimised the peak and idle speeds?Is it possible for some loads that the Pi initially runs at the highest speed and then throttles down to the lowest? If so, that may pick up two extreme modes of operation both of which are inefficient from a get the work done using the least amount of energy point of view.
Indeed, although we are constantly looking for better settings. The main problem is lack of PLL's and PLL dividers on the SoC to provide all the different constant clocks required to run the system, but still allow the governor to raise and lower the CPU clock as necessary.jbudd wrote: ↑Wed Aug 28, 2019 5:33 pmMaybe the people who designed it have already optimised the peak and idle speeds?Is it possible for some loads that the Pi initially runs at the highest speed and then throttles down to the lowest? If so, that may pick up two extreme modes of operation both of which are inefficient from a get the work done using the least amount of energy point of view.
Really not sure what you are saying.Moonmarch wrote: ↑Wed Aug 28, 2019 6:05 pmA new software update should lower the clock speed to reduce the computer temperature this is important for people who do not monitor computer temperatures, which is the reason why the computer not reaching max load temperature is necessary if the computer does overheat one day, how do you know if the person using the computer knows how to cool down the computer, watching videos about adding heat sinks to the RPI computer the square heat sinks are not very effective at lowering computer temperatures which means you will not be able to passively cool down the RPI computer without buying a aluminum case or use internal fan, here is a link to the RPI aluminum case video:
Flirc Case For The Raspberry Pi 4 - The Best Pi4 Case! - First Look And Thermal Testing:
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For those use cases I wouldn't even bother with extra cooling.ProDigit wrote: ↑Fri Aug 30, 2019 4:46 amIf you're mostly running the Pi passive (eg: terminal, chat server, bit torrent client, media server, or other small programs from terminal that only require small load times), I would go with a huge passive heat sink. One of those that's almost the size of the pi itself.
They act like a heat buffer (remove heat efficiently from the CPU for short duration, until the sink is saturated); but also need a little longer to cool down.
You don't. At stock clocks the heatsink cases floating around will remove enough heat to stay way under 80°C. In my case it was 68°C and 59 under absolutely full load using cpuburna53. Former was with way higher ambient temp hence why the increse. If you overclock a fan (plus heatsink if you want) will do the job.