One of the most popular experiments to do with your Raspberry Pi is overclocking it. Overclocking is fairly simple to do on the Raspberry Pi, however, it requires additional cooling in the form of heatsinks and fans to ensure that the Pi doesn't overheat and damage itself.
Hey guys how are you going? It’s Sam here from Core Electronics and today we’re going to be taking a look at how to cool your Raspberry Pi 3. Now why do we need to cool our Raspberry Pi? It’s a good question and you might think that surely the device should run as it is and it should run without any issues and that is partly true but with computers there’s a whole bunch of different factors to take into account for example it depends on how many applications you’re running, how much RAM is being used, how intensively your processor is being used and how much energy it’s drawing - you know all that kind of stuff comes into play. Now you might have noticed if you plugged your Raspberry Pi in the usual use the main System On Chip SoC just there it does get a little warm but not out of the ordinary. However if you’re doing really intense applications such as perhaps running a RetroPie setup or watching alot of HD Video, you’ll notice that it really starts to heat up and it’s not too much of an issue except that with processes the performance can actually start going down and the system can become more unstable the hotter the chip gets so we want to cool our Raspberry Pi if we want to be using it for any serious work. The other reason is this is the first in a 3 part series where we look at cooling, stress testing and overclocking in your Raspberry Pi. We get to stress testing in the next video and over clocking a little bit later. But when we’re doing that if we want to really put our Raspberry Pi through its paces, its going to generate a lot of heat because it’s running at its maximum potential and we need to cool it down. Likewise if you’re overclocking it, you’re running the Pi faster and in a greater capacity than it’s normally used to so you need to make sure you can keep those chips cool otherwise it’s going to become unstable, crash and shut down.
So what are we cooling? Well there’s three main chips on the Raspberry Pi, there’s the System on Chip here which is the main one and it contains the CPU the GPU and all the other related peripherals, here we’ve got the Ethernet and USB Bus Controller and on the back side we’ve got the SD RAM chip. Now a mistake that a lot of people make is thinking they need to cool all of those and indeed alot of Raspberry Pi Heat Sink Kits will come with one larger Heat Sink and two smaller Heat Sinks for cooking every chip but it’s not quite true. You see while in the original Raspberry Pi design there was an electrical design element which caused the Ethernet and USB Bus Chip to heat up quite a lot and that was why people needed to cool it. However that was fixed in a later edition of the Board and now it’s no longer an issue. So the main chip we really need to focus on cooling is the System On Chip, the main Broadcom BC2837 if you’re using a Raspberry Pi3 and we’ll be using a Raspberry Pi 3 for most of these tutorials however it’s still relevant to the other Raspberry Pi models as well. You’ll notice here I’ve got quite a large heat sink on this one, the larger the heat sink the more heat it can dissipate. I’ve also got a heat sink mounted on the SD RAM chip and that’s because as you’ll find out in a later tutorial I was overclocking the SD RAM as well so I wanted to make sure that was running nice and cool. So how do we go about cooling it - heat sinks, fans, some people prefer to water cool, whats the go? Well first of all let’s get it aside that you do, you do not need to water cool, liquid nitrogen cool or any other exotic form of cooling need to cool your Raspberry Pi under anything but the most ridiculous and extreme usage. A heat sink and a fan is going to be just fine.
See this set up here, I’ve got one of our Raspberry Pi Australia cases and it comes with a built in fan and I’ve added a heat sink there and the fan sits just nicely on top of the heat sink and its got 5V and it’s got a positive and a ground wire that can plug straight in to the GPIO pins. Neat little case, it’s one of the best ways to keep your Pi that extra bit cooler for nothing at all. So passive cooling, you might have heard that thrown around a little bit and passive cooling refers to when you are not using any extra energy to cooler Raspberry Pi so the fan is active cooling because it is consuming electricity to cool your Pi whereas a heat sink is just a great little hunk of metal designed to draw heat away from the chip.
So you’ll see quite a lot of heat sinks, we’ve got a large range of them on our website and which ones going to be best. Well it depends, I’ve got a couple of small ones here, this is an aluminium fin heat sink and this is a copper heat sink with you can see it’s got little rectangular risers rather than the long fins that this one has here. This one again is aluminium but much bigger and has those same fins. Now these heat sinks come with some thermal padding on the back, thermal tape if you will, and that’s designed so that when you press it on to the chip it makes a really really good contact because the surface of the metal isn’t perfectly smooth, there’s microscopic imperfections, divots, ridges on that that are going to cause it to not make perfect contact with the chip and as a result pockets of air get trapped under there and air is a really good insulator which is going to stop heat being drawn up by that heat sink. Now even better than that is thermal paste, if you’ve used computers before you’ll know what thermal paste is and it is a paste that is thermally conductive and the best way to use that is if it does come with thermal pads, scrub that off with some Isopropyl and get a nice clean surface and put some thermal paste, a very thin layer on your heat sink and a very thin layer on your chip an away you go. Thermal tape works pretty well but not quite as well as thermal paste but both of them are much better than just the raw heat sink on top. Be wary though some heat sinks can have really thick adhesive tape, talking a couple of mm’s thick here and thats really bad because that tape will act like a complete insulator and again it will stop any heat being drawn up.
So that’s a bit about cooling now there’s a bit of a debate when using fans about whether you want to push air, push cool air in on to the heat sink or draw the hot air out. Now normally in a standard cooling case for example say a computer it will have both, it will have intake fans and exhaust fans to pull cool air in and and exhaust hot air out where it’s being most generated. But with the Raspberry Pi we don’t really have the luxury of having all these different fans going on so we have to choose carefully. Now I’ve got this particular fan set up to draw hot air out of it and I’m going to explain why. There’s a diagram in the tutorial here, and so the idea is is that the main heat sink will have a really good capacity to absorb or to dissipate most of the heat coming from the chip. Now you see the fins there? Thats to allow the air to brush through the heat sink to cool the heat sink itself down. That’s our goal, we’ve taken care of the chip and now we need to cool the heat sink down so we can further cool the chip down. Now if we’re drawing hot air we’ll notice there’s room through the board underneath for more air to be drawn up which is really good, so if we’re drawing hot air out it’s also going to pull cool air in and cool that heat sink and with a single fan, especially a small one like this it’s probably going to be the most efficient way to cool your Pi. However having a fan drawing cool air in and pushing it over the heat sink and drawing the hot air out from on top because hot air rises is going to be the most efficient way to cool your Pi. That’s just a little set up we’ve got, I’ve been able to overclock this guy as far as the silicon itself is stable, run stress testing on it and it hasn’t overheated, it’s a fantastic setup.
That’s how we do it, now there is one last thing if you are very very serious about cooling your Raspberry Pi, we put this contraption together. Now what is this you might ask? This is a Peltier Module and it is complete overkill but it was a lot of fun anyway. Now what a Peltier Module does is as a quick overview, is it has 2 plates and uses a very specific construction to create a heat differential when voltage and current is running through it, sorry when voltage supply and current is running through it I should say which causes one side to get really really cold and the other side to get really really hot. Now it’s got this whopping big heat sink on there because you want to keep the hot side as cool as possible because if the hot side temperature increases the cold side temperature will increase as well and it’s got a fan to draw hot air away from the heat sink. We’ve got another 120mm computer case fan to mount it on top and we can slot a Raspberry Pi in there and with the heat sink making contact with the cold side of the Peltier Module it will keep your Pi frosty under the most intense conditions. I know I couldn’t get this Pi over about 35 degrees which is practically frozen in the realm of computers - it’s pretty cool! Complete overkill but a very fun project if you are interested to see how far you can push your Raspberry Pi.
So that’s a bit of an overview on cooling and then the next video we’re going to take a look at Stress Testing and making sure that our cooling system is up to scratch and how we can put our Pi through its paces and measure the temperature so take a look at that. This is the first part of Cooling, Stress Testing and Overclocking your Raspberry Pi. I hope you guys enjoyed it, if you want to know anything else then get this conversation started in the comments below, that’s all for now, have a great day guys :-)