The Raspberry Pi 4 needs a fan • Hacker News Board

Re: The Raspberry Pi 4 needs a fan

#161

Post by darkpuma » Wed, Jul 17, 2019, 6:28 PM UTC

guelo wrote: post #155

ryanmercer wrote: post #148

Earlier quoted context omitted.

To add to this, I wonder if a properly designed case could create a chimney effect (not unlike the crossdraft kiln Primitive Tech made in his most recent video) where escape heat is drawing in cooler air in such a fashion as to be adequate enough fo the vast majority of applications. Not that fans need to be very loud, or even spin very fast for something of this size, I imagine relatively low RPMs (probably sub 100…

But then you would need a "This Side Up ↑" label and you would only be able to orient the case in one way.

It would work for most people, wouldn't it? And the people putting their raspis into unusual scenarios for which the case was poorly suited could simply choose to not use that particular case. Encouraging thermal convection (ideally flowing over a proper finned passive heatsink) with a chimney design seems like a pretty good idea to me.

Re: The Raspberry Pi 4 needs a fan

#162

Post by neetdeth » Wed, Jul 17, 2019, 6:28 PM UTC

ryanmercer wrote: post #148

pslam wrote: post #146

This article is actually describing how the Raspberry Pi 4 does NOT need a fan. This is not the 1990s. It is perfectly acceptable and even advantageous to design for a high peak:normal load ratio, with thermal throttling. In this case, it allows for a compact, cheap, fanless design for the vast majority of users. There is no evidence the heat dissipated will impact lifespan. It is common for the components picked out…

To add to this, I wonder if a properly designed case could create a chimney effect (not unlike the crossdraft kiln Primitive Tech made in his most recent video) where escape heat is drawing in cooler air in such a fashion as to be adequate enough fo the vast majority of applications. Not that fans need to be very loud, or even spin very fast for something of this size, I imagine relatively low RPMs (probably sub 100…

Re: The Raspberry Pi 4 needs a fan

#163

Post by godelski » Wed, Jul 17, 2019, 6:32 PM UTC

delinka wrote: post #103

book-mind wrote: post #62

Earlier quoted context omitted.

That image is still highly misleading, you can see from the overlayed optical image that the CPU is not coated. Ideally you'd want to coat any metal surface with black epoxy, and set the IR camera Emissivity Coefficient to 0.9 (the coefficient for black epoxy).

Why would the overlay need to be with the board that had a coating? Buy two boards, cover the parts on one board that are silver, shoot IR. Use second board for visible wavelength photo, combine for a beautiful overlay result.

Why would you assume that they are different boards?

Re: The Raspberry Pi 4 needs a fan

#164

Post by microtonal » Wed, Jul 17, 2019, 6:33 PM UTC

jrockway wrote: post #101

adrianmonk wrote: post #22

> If you run computing hardware at its thermal capacity for long periods of time, this will cause more wear on the parts than if they are run well inside their limits. So I have a moderately increased likelihood of, at some indefinite point in the future, having to spend a whole $35 to replace the Raspberry Pi. I can prevent this by spending extra money (and time) up front. In some cases, it might be worth it. Maybe…

I think if you focus too much on "$35" you will be very disappointed with the rpi. You need a power supply, that's $10. You need an SD card, that's $10. You need a case, that's $10. You need a micro HDMI to HDMI cable or two, that's $10. You need a fan, that's $10. If you mentally decide "the Raspberry Pi is a $100 computer all-in" you will be much happier. You won't buy one to sit in a drawer (as many on HN have com…

If you mentally decide "the Raspberry Pi is a $100 computer all-in" you will be much happier. You won't buy one to sit in a drawer (as many on HN have complained about), and you won't try to use a USB charger from your phone from 1992 and that SD card you got with your sandwich at IKEA and be disappointed that it's not very reliable.

It's a bit of a shame that what started out as an educational computer is about $100 to get started properly. Nowadays I recommend Micro:Bit for tinkering (our daughter has one, she likes it very much). It's about 20 Euro and you have everything needed (including a battery pack if you want to use it portably).

If you want a machine that fore serious work (NAS, media center, low-end desktop), before spending $100 one should at least consider spending a bit more and get a NUC. You can buy a NUC for around 120 Euro, then you have to add memory and storage. But at least, you get a machine with fast I/O, faster CPU, and is more expandable. It also does supports 4K and h.265 decoding like the Pi 4.

Re: The Raspberry Pi 4 needs a fan

#165

Post by darkpuma » Wed, Jul 17, 2019, 6:34 PM UTC

marcosdumay wrote: post #120

AnIdiotOnTheNet wrote: post #30

Earlier quoted context omitted.

Yeah, I'm kinda wondering just what the Pi is supposed to be at this point. Is it still an inexpensive low power device for teaching basic computer science? Because it seems like it's more for making Kodi boxes or the worlds most powerful LED blinkers.

The Pi4 is overpowered for a Kodi box. That said, there is a huge number of applications for overpowered LED blinkers, and no lack of people to use them. And there is a great deal of educational value on having those boards available and easy to get. Besides, it's becoming hard to find people without access to a machine where they can learn basic computer science. So this one niche is closing down, while the Pi is st…

> The Pi4 is overpowered for a Kodi box.

Even for software decoding of codecs or containers unsupported by the hardware acceleration? If that's true, I might have to get one.

Re: The Raspberry Pi 4 needs a fan

#166

Post by ars » Wed, Jul 17, 2019, 6:35 PM UTC

The POE hat comes with a built in fan, so might be a nice option.

https://www.raspberrypi.org/products/poe-hat/

Re: The Raspberry Pi 4 needs a fan

#167

Post by londons_explore » Wed, Jul 17, 2019, 6:37 PM UTC

danaos wrote: post #79

LeonM wrote: post #6

So does the pi 3 if you stick it in a case, even with a heatsink. I was using a pi 3 with a heatsink in the official case to play a h265 movie (which will be software decoded on a pi3). After about 10 minutes I noticed it started dropping frames and it displayed the thermometer symbol in the top-right of the display. When I removed the top lid from the case, the temperature dropped enough for the thermometer icon to…

Well the pi3 does not support h265 acceleration natively, it should have been better to use it on h264 movies.

Hardware acceleration comes in degrees... It's totally possible to hand-code some GPU firmware to decode any bitstream far more efficiently than the CPU can do it...

It's just a lot of work, and either Broadcom hasn't done it, or they don't want to license it to the Raspberry Pi.

Re: The Raspberry Pi 4 needs a fan

#168

Post by AnIdiotOnTheNet » Wed, Jul 17, 2019, 6:38 PM UTC

kingosticks wrote: post #159

AnIdiotOnTheNet wrote: post #142

Earlier quoted context omitted.

Because the two goals are somewhat incompatible. The more powerful they make the hardware to please one crowd the less they can meet the "low power", and to a lesser extent price (need a fan now, etc), goals.

I can't agree with that conclusion. Where has the "low power" goal come from (as if 15W wasn't low power anyway). And as has been said already, you 100% do not need to actively cool a RPi 4 to teach kids to code with it!

> I can't agree with that conclusion. Where has the "low power" goal come from

...ok, checking again I may have read that into the goals when it wasn't.

Re: The Raspberry Pi 4 needs a fan

#169

Post by geerlingguy » Wed, Jul 17, 2019, 6:38 PM UTC

pslam wrote: post #146

This article is actually describing how the Raspberry Pi 4 does NOT need a fan. This is not the 1990s. It is perfectly acceptable and even advantageous to design for a high peak:normal load ratio, with thermal throttling. In this case, it allows for a compact, cheap, fanless design for the vast majority of users. There is no evidence the heat dissipated will impact lifespan. It is common for the components picked out…

I am not directly the target market, no. And the throttling itself is an indication that the heat was designed/accounted for in the Pi's design.

However, to say that the majority of users don't need better cooling, and it won't cause problems most of the time, seems inaccurate. If you use a microSD card to boot/run the Pi, how many of them are rated for blisteringly-hot operating conditions 24x7 (many people using the Pi as a computer will have it booted pretty much all day and just turn off the monitor, or go to screensaver).

And I have already had one PoE HAT's PoE socket pop partly off the board when removing it from a Pi 3 B+. Partly due to stress of flexing the board, definitely... but that kind of tiny solder joint on a part that is stressed when making a connection is exactly the point of failure that may not be directly caused by, but is definitely not helped by thermal stress.

Re: The Raspberry Pi 4 needs a fan

#170

Post by geerlingguy » Wed, Jul 17, 2019, 6:39 PM UTC

ryanmercer wrote: post #148

pslam wrote: post #146

This article is actually describing how the Raspberry Pi 4 does NOT need a fan. This is not the 1990s. It is perfectly acceptable and even advantageous to design for a high peak:normal load ratio, with thermal throttling. In this case, it allows for a compact, cheap, fanless design for the vast majority of users. There is no evidence the heat dissipated will impact lifespan. It is common for the components picked out…

To add to this, I wonder if a properly designed case could create a chimney effect (not unlike the crossdraft kiln Primitive Tech made in his most recent video) where escape heat is drawing in cooler air in such a fashion as to be adequate enough fo the vast majority of applications. Not that fans need to be very loud, or even spin very fast for something of this size, I imagine relatively low RPMs (probably sub 100…

This is why I suggest in the video to just stick some ventilation holes in the top cover. Instead of the heat pooling in that area, it could escape, and there would be some natural convection—in through the gaps around the ports, out through the top. It wouldn't be as good as a fan, but definitely better than slapping a heat sink inside the case.