jamesh
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Re: Raspberry Pi 4 temperature

Sun Jun 30, 2019 2:48 pm

ndrw wrote:
Sun Jun 30, 2019 1:27 pm
jamesh,

Thank you for the info. This would be consistent with what I am seeing - lowering idle cpu frequencies has almost no impact on power consumption but changing (increasing) supply voltage increases power consumption dramatically.

I will wait for the updated vli firmware, any eta would be greatly appreciated.

Anu idea why supply voltage cannot be lowered in RPi4?
I'm no expert on the power requirements, but we are constantly looking for ways to decrease power and heat. Might be some areas in clock management that will help. If you can reduce clocks you use less power, and therefore produce less heat.
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Re: Raspberry Pi 4 temperature

Sun Jun 30, 2019 3:46 pm

jamesh wrote:
Sun Jun 30, 2019 2:48 pm
I'm no expert on the power requirements, but we are constantly looking for ways to decrease power and heat. Might be some areas in clock management that will help. If you can reduce clocks you use less power, and therefore produce less heat.
I am almosr certsinly much less of an expert on power requirements and management than you are James, but (as well as reducing the heat) would not 'reducing clocks' also lower the actual power output of the Pi, which would not be appreciated by many users?

Just a quick thought anyway!

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Re: Raspberry Pi 4 temperature

Sun Jun 30, 2019 5:21 pm

It's certainly possible that power usage and thermal tunings affect performance. Some past tunings have reduced performance (on Pi 3B or Pi 3B+, don't remember which one). This also applies to the PCIe power management fixes. I think it's fine to take a small hit for significantly reduced power usage, though.

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Re: Raspberry Pi 4 temperature

Sun Jun 30, 2019 5:31 pm

jahboater wrote:
Sun Jun 30, 2019 1:50 pm
If you mean "over_voltage=-2"
That seems to be working now.
Can you clarify that? Were there any recent fixes?

I tried that yesterday with everything up to date. Both -1 and -2 values resulted in ~1.1V supply voltage (looks like a maximum voltage the regulator can output). Needless to say, temperatures were over 80C and the CPU was being throttled all the time.

Running CPU at lower (0.5x) frequencies made no difference to system power consumption. But I wouldn't mind reducing CPU speed at all if that meant I can use RPi4 with a passive cooled case.

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Re: Raspberry Pi 4 temperature

Sun Jun 30, 2019 5:41 pm

It is probably common knowledge by now, and I think has been mentioned on here already, but I have just read that: "The Raspberry Pi Foundation has a new firmware for the VLI USB controller that is said to lower idle power consumption by 10%. They’ll release it in a few weeks."

Hopefully that will help things a bit, although it wouldn't surprise me if there is a bit more "tweaking" going on behind the scenes at the moment also!

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Re: Raspberry Pi 4 temperature

Sun Jun 30, 2019 5:50 pm

RPi4 simply needs cooling, and it doesn't have to be any big noisy thing: when using 3cm, undervoltaged, (3.3 instead of 5V) slow rotating, silent fan. my RPi4 never reached 70C, even overclocked and overvoltaged.

I will also try FLIRC case when available.

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Re: Raspberry Pi 4 temperature

Sun Jun 30, 2019 8:17 pm

I agree at the moment it looks like the Pi4 will need some form of active cooling if it's going to be used in an enclosurre.

I honestly can't see how their Desktop Kit would work without throttling: https://thepihut.com/products/raspberry ... 4004440126

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Re: Raspberry Pi 4 temperature

Sun Jun 30, 2019 9:19 pm

I've spent some time today investigating the differences between my Pi 3 and Pi 4 both when enclosed in their respective official cases. As this thread indicates the Pi 4 is a toasty board in comparison to it's previous incarnation. As the power draw has increased from 2.5W to 3.8W when idle, this > 50% increase in power usage is going to generate a lot more heat, which the new case doesn't seem to have been designed to manage.

It could be that the power draw is significantly higher than intended, I hope it is. @JamesH can you comment on the expected power usage of a notionally idle Pi 4?

My blog post: https://www.martinrowan.co.uk/2019/06/r ... -enclosed/

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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 5:10 am

martinrowan wrote:
Sun Jun 30, 2019 8:17 pm
I agree at the moment it looks like the Pi4 will need some form of active cooling if it's going to be used in an enclosurre.

I honestly can't see how their Desktop Kit would work without throttling: https://thepihut.com/products/raspberry ... 4004440126
Cooling a closed off system that does not allow air ventilation isn't very efficient. The official RPi4 case isn't suited for active cooling.
At least with the RPi3 case you could take the top and the side panels off...

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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 7:19 am

martinrowan wrote:
Sun Jun 30, 2019 9:19 pm
I've spent some time today investigating the differences between my Pi 3 and Pi 4 both when enclosed in their respective official cases. As this thread indicates the Pi 4 is a toasty board in comparison to it's previous incarnation. As the power draw has increased from 2.5W to 3.8W when idle, this > 50% increase in power usage is going to generate a lot more heat, which the new case doesn't seem to have been designed to manage.

It could be that the power draw is significantly higher than intended, I hope it is. @JamesH can you comment on the expected power usage of a notionally idle Pi 4?

My blog post: https://www.martinrowan.co.uk/2019/06/r ... -enclosed/
Again, depends on definition of idle. Booted to console? Booted to desktop? Got any background task runnings? Using 4kp60?

Not that I have specific figures, but could generate some.
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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 8:04 am

Again, depends on definition of idle. Booted to console? Booted to desktop? Got any background task runnings? Using 4kp60?

Not that I have specific figures, but could generate some.
Per my blog post, my testing method was to boot both a Pi 3 and a Pi 4 to a Desktop, tested with and without 4k enabled. Nothing running in the background (except rpi-monitor), load average near zero.

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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 8:40 am

martinrowan wrote:
Mon Jul 01, 2019 8:04 am
Again, depends on definition of idle. Booted to console? Booted to desktop? Got any background task runnings? Using 4kp60?

Not that I have specific figures, but could generate some.
Per my blog post, my testing method was to boot both a Pi 3 and a Pi 4 to a Desktop, tested with and without 4k enabled. Nothing running in the background (except rpi-monitor), load average near zero.
4kp30 or 4kp60? They have different clocks and therefor different heat loads. tvservice -s will indicate the specific speed.
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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 10:08 am

Things like around Pi 2:

https://www.raspberrypi.org/forums/view ... p?t=100239

Pi 2 runs 900Mhz in default and is changeable to 1000 Mhz through `sudo raspi-config`.

Pi 4 may need a stage of the low speed clock for heat-treating to fit with cases which have no cooling system.

And the history of Raspberry Pi and Heat Sink:

https://www.raspberrypi.org/forums/view ... hp?t=13080

I'm happy that several projects about fan coolers is going on. I would like the new topic for fan coolers.
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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 10:32 am

When idle and using onDemand cpu governor the Pi 4 was running at just 600MHz already.

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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 11:07 am

martinrowan wrote:
Mon Jul 01, 2019 10:32 am
When idle and using onDemand cpu governor the Pi 4 was running at just 600MHz already.
Pi 4 implements the CPU governor for its variable clock speed. The CPU governor can refrain from using higher clock speed. It seems VC4's work.

https://www.raspberrypi.org/documentati ... locking.md

So I checked about overclocking in config.txt.

The CPU governor equals `force_turbo=0`?
Last edited by jimmyken on Mon Jul 01, 2019 11:17 am, edited 2 times in total.
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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 11:08 am

Might be some mileage in dropping the ARM idle frequency, in config.txt

arm_freq_min=300
or
arm_freq_min=150.

If anyone want to see if that makes much of a difference might be worth a go. Tiny performance hit as the CPU ramps up when started to load, but in my testing in the open air, seemed to get a 1deg drop in idle temps with 150.
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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 11:14 am

If you are running Raspbian Lite headless, is it worth reducing gpu_freq or core_freq?

I read somewhere that on the Pi4, the core_freq doesnt affect the L2 cache speed.

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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 11:21 am

jamesh wrote:
Mon Jul 01, 2019 11:08 am
Might be some mileage in dropping the ARM idle frequency, in config.txt

arm_freq_min=300
or
arm_freq_min=150.

If anyone want to see if that makes much of a difference might be worth a go. Tiny performance hit as the CPU ramps up when started to load, but in my testing in the open air, seemed to get a 1deg drop in idle temps with 150.
Seems lower ARM idle frequency is made with `force_turbo=0`, it's the default setting.
`arm_freq` is the maximum speed. The combination of these settings helps its heat-treating.
Last edited by jimmyken on Mon Jul 01, 2019 11:29 am, edited 1 time in total.
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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 11:24 am

jimmyken wrote:
Mon Jul 01, 2019 11:21 am
jamesh wrote:
Mon Jul 01, 2019 11:08 am
Might be some mileage in dropping the ARM idle frequency, in config.txt

arm_freq_min=300
or
arm_freq_min=150.

If anyone want to see if that makes much of a difference might be worth a go. Tiny performance hit as the CPU ramps up when started to load, but in my testing in the open air, seemed to get a 1deg drop in idle temps with 150.
Seems lower ARM idle frequency is made with `force_turbo=0`, it's the default setting.
You don't need force_turbo, just set arm_freq_min to whatever value you want. By default its 600. This is the minimum frequency the ARM can be allowed to drop to.

You can measure the current value

`vcgencmd measure_clock arm`
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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 11:41 am

jahboater wrote:
Mon Jul 01, 2019 11:14 am
If you are running Raspbian Lite headless, is it worth reducing gpu_freq or core_freq?

I read somewhere that on the Pi4, the core_freq doesnt affect the L2 cache speed.
I'd like to ask the all about these frequencies to Broadcom having right answers.
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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 1:20 pm

jimmyken wrote:
Mon Jul 01, 2019 11:41 am
jahboater wrote:
Mon Jul 01, 2019 11:14 am
If you are running Raspbian Lite headless, is it worth reducing gpu_freq or core_freq?

I read somewhere that on the Pi4, the core_freq doesnt affect the L2 cache speed.
I'd like to ask the all about these frequencies to Broadcom having right answers.
All this stuff is maintained by us at Raspberry Pi trading. What are your questions? Does this page help?

https://www.raspberrypi.org/documentati ... locking.md
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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 2:02 pm

jamesh wrote:
Mon Jul 01, 2019 1:20 pm
All this stuff is maintained by us at Raspberry Pi trading. What are your questions? Does this page help?
My question was:-
For a headless (Raspbian Lite) Pi4, are there any performance downsides when reducing core_freq and/or gpu_freq to save power/reduce heat?

In the overclocking link it says
L2 cache benefits only the Pi Zero/Pi Zero W/ Pi 1, there is a small benefit for SDRAM on the Pi 2/Pi 3, and there is no effect on the SDRAM on the Pi 4B
which is helpful. I just wondered if there were any other reasons not to reduce core_freq as far as possible?

gpu_freq should set core_freq

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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 3:09 pm

jahboater wrote:
Mon Jul 01, 2019 2:02 pm
For a headless (Raspbian Lite) Pi4, are there any performance downsides when reducing core_freq and/or gpu_freq to save power/reduce heat?
core_freq affects the main AXI bus the ARM and other hardware use to access sdram (on all models of Pi).
Reducing core_freq directly reduces the sdram bandwidth available which will reduce performance of arm code that accesses significant memory.

If the arm is using a small data set that fits within its L2 cache (1MB on Pi4) then the affect may be minimal.

The usual configuration links core_freq to arm_freq using the ondemand cpufreq governor which means core_freq is high when arm is busy and low when idle.

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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 4:40 pm

Thanks Dom, I appreciate the explanation.

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Re: Raspberry Pi 4 temperature

Mon Jul 01, 2019 5:40 pm

jamesh wrote:
Mon Jul 01, 2019 8:40 am
martinrowan wrote:
Mon Jul 01, 2019 8:04 am
Again, depends on definition of idle. Booted to console? Booted to desktop? Got any background task runnings? Using 4kp60?

Not that I have specific figures, but could generate some.
Per my blog post, my testing method was to boot both a Pi 3 and a Pi 4 to a Desktop, tested with and without 4k enabled. Nothing running in the background (except rpi-monitor), load average near zero.
4kp30 or 4kp60? They have different clocks and therefor different heat loads. tvservice -s will indicate the specific speed.
Sorry, I should have been clearer, the monitor isn't a 4k display, it's a 3440x1440 display. I tested with the config for 4k enabled vs commented out.
Output of tvservice -s is:

Code: Select all

state 0xa [HDMI CUSTOM RGB full unknown AR], 3440x1440 @ 49.00Hz, progressive
Being blunt, either the power draw and therefore heat generated by the Pi 4 is above the expected norm, or the official Raspberry Pi 4 case is unfit for the intended purpose since thermal limits are hit even when idle. Hopefully, it's the former and something which can be addressed in software.

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