bcadej
Posts: 12
Joined: Sat May 04, 2019 7:35 pm

Why is temperature of CPU so high?

Sat May 25, 2019 8:08 pm

I‘ve copied the Raspbian Stretch Lite to the card, put it into Pi, boot.
Then I’ve played with some settings

Code: Select all

sudo raspi-config
(mostly locale) and setup wireless, …
I went away for a while, came back and made some more settings.

When I touched the Pi, it seemed hot to me.

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pi@pita:~ $ cat /sys/class/thermal/thermal_zone0/temp
48312

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pi@pita:~ $ vcgencmd measure_temp
temp=48.3'C


The Pi is on the table. No heat sink. No box. Room temperature is about 23'C.

Why is the temperature so high? :o I haven’t done any intensive tasks. Yet. 8-)

Andyroo

Re: Why is temperature of CPU so high?

Sat May 25, 2019 8:15 pm

What type of Pi do you have?

My Zero W running as Ad Block is at 41 - room is about 20

A Pi 3B near it doing nothing is at 46

LTolledo
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Re: Why is temperature of CPU so high?

Sat May 25, 2019 8:29 pm

That 48deg is still under "optimal temp" at that condition

if it is just idle and temp is 60 and above.... that should be a point of concern...

better encase it to prevent accidental shorts that can kill your RPi

if you're getting ambient of 40C, better attach heatsink and fan

if you dont like fans, get a bigger heatsink....
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dl324
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Location: Pacific Northwest, USA

Re: Why is temperature of CPU so high?

Sat May 25, 2019 8:46 pm

bcadej wrote:
Sat May 25, 2019 8:08 pm
When I touched the Pi, it seemed hot to me.

Why is the temperature so high? :o I haven’t done any intensive tasks. Yet. 8-)
48C doesn't seem excessively high to me. I ran my Pi Zero at about 90% CPU utilization for several hours and the core temperature was reported as 46C. It didn't even feel warm to me when I touched the package.

I wouldn't be concerned unless the temperature was closer to 100C. From what I understand, the CPU will throttle itself.

If you're paranoid, you can attach a heatsink.

Ernst
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Re: Why is temperature of CPU so high?

Sat May 25, 2019 9:04 pm

I am running two long time "scientific" ;) experiments on a Pi 3B for a few weeks now.
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Imperf3kt
Posts: 3219
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Location: Australia

Re: Why is temperature of CPU so high?

Sat May 25, 2019 10:10 pm

That temperature is well within normal operating temperature.
It is a little high but not overly so.
My Pi idles at around 38°C but I should note mine has a small chunk of aluminium on it (not a heatsink, just a slab of aluminium I cut and mounted)

You don't need to worry until about 70°C, and higher. It should not reach higher than about 85°C due to self regulation (throttling)

The Pi is an ARM based device, it runs fine at hotter temperatures than you'd expect.
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W. H. Heydt
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Re: Why is temperature of CPU so high?

Sat May 25, 2019 11:56 pm

As for why it's "hot" (or, as others have pointed out, not as hot as all that)... The encapsulation plastic, an insulator. It is consuming power. The power is dissipated as heat. So the processor heats up until the heat that can be dispersed through radiation, convection and conduction is equal to the heat being generated by consuming electrical power.

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