Using pencil lead to cool a Rpi?

[TrooperZ]

My RPi has gotten to really high temps (ie: 70.9c) and I don't really want to buy a fan, so I tried using pencil lead (0.7) to cool it down b/c it is a good heat conductor. It managed to cool it only by 1c.

Is this a good idea?

[jahboater]

My RPi has gotten to really high temps (ie: 70.9c) and I don't really want to buy a fan, so I tried using pencil lead (0.7) to cool it down b/c it is a good heat conductor. It managed to cool it only by 1c.

1C is not enough. You need 11C to avoid it throttling with the latest Raspbian.

A coin may be better - a couple more degrees!

No need to buy a fan, they can be noisy and introduce a moving part.
You can get cheap stick-on passive heat sinks for a UK pound or two, or you could get a case (the FLIRC case) that will act as a big heat sink:
https://www.amazon.co.uk/FLIRC-Raspberr ... case&psc=1

I like the new Kintaro heat sink:
https://www.amazon.co.uk/Kintaro-Raspbe ... 3+heatsink
it is really very effective and low profile.

[B.Goode]

From: https://www.raspberrypi.org/blog/raspbe ... le-now-35/

Clocking, voltages and thermals
The improved power integrity of the BCM2837B0 package, and the improved regulation accuracy of our new MaxLinear MxL7704 power management IC, have allowed us to tune our clocking and voltage rules for both better peak performance and longer-duration sustained performance.

Below 70°C, we use the improvements to increase the core frequency to 1.4GHz. Above 70°C, we drop to 1.2GHz, and use the improvements to decrease the core voltage, increasing the period of time before we reach our 80°C thermal throttle; the reduction in power consumption is such that many use cases will never reach the throttle. Like a modern smartphone, we treat the thermal mass of the device as a resource, to be spent carefully with the goal of optimising user experience.

Somewhere, I can't find it right now, is another more detailed blog post from one of the engineers involved describing some of the fine detail of the careful design of the power supply and thermal dissipation.

Compared with that attention to detail, adding a bit of broken pencil seems a trifle crude?

[drgeoff]

@B.Goode

Isn't there a thread somewhere about the 70 degree figure being incorrect? The down-clocking starts at 60 degrees.

Edit. Found it. viewtopic.php?f=63&t=217056

[B.Goode]

The detailed follow up articles I recalled seeing are here https://www.raspberrypi.org/blog/pi-power-supply-chip/ and here https://medium.com/@ghalfacree/benchmar ... 122cf3d806.

[TrooperZ]

I am not overclocking at all. I only do stack overflow, google hangouts and other basic coding and search

[neilgl]

What model is your pi?

[mahjongg]

Pencil lead (graphite) is highly electrically conductive, if it spreads over your PI it can short things together.

Instead use cooling paste, like arctic silver to mount a small heat sink, or even just a coin on top of the SoC so the heat can spread better..

[jahboater]

Start by mounting the Pi on edge. It should be a few degrees cooler just by doing that - normal convection.
Obviously it should be in free air, outside of a case (unless its in a special cooling case like the FLIRC).

You can get a cheap heatsink such as this for $1.95 that will stick on with thermal tape:
https://www.adafruit.com/product/3082
Make sure the fins are aligned vertically.
That should drop it a few degrees more.

If you want even more cooling, the Kintaro heat sink I linked to above is brilliant. It is so good here is the link again:
https://www.amazon.co.uk/Kintaro-Raspbe ... 3+heatsink
Brilliant !!!
Note it is bolted on so doesn't rely on sticky thermal tape, instead it uses proper thermal paste which is much more effective.
Its mass is 23g adding to the already considerable thermal inertia of the Pi3B+.

[TrooperZ]

I have a RPi 3b FYI, and i have sealed the graphite together and onto my heat sinks and opened the top of my case and made holes on the bottom. I have added coins (3 quarters on large + 8 sticks of lead and 1 dime + 4 sticks of lead on small) The highest the temperature has been is 68c. With out these, the highest was 82c

[Imperf3kt]

82℃ is very high (thats also the point a Pi3b will begin throttling)

How do you manage to get your Pi that hot? Highest I ever reached was ~72℃ and that was while running cpuburn on my Pi in a fully enclosed environment while sitting on my bed, half wrapped up in blankets.

Also, isn't arctic silver, also conductive. Be sure to secure that heatsink properly, or the thermal compound may run once heated.

[TrooperZ]

I mentioned above what I do