Gadgetory

everyone we're doing the new TLDR series that is too long didn't read so you've seen some of our long-form articles on the website but this will be recapping those very quickly so the first TL DR episode we'll be talking about CPU coolers and how they work we talk about the materials comprising the copper cold plate or aluminum cold plate thermal conductivity heat pipe wicking vapor chambers and the fins and how it all actually works to conduct heat away from your CPU cores let's start with a bottom-up workflow of how a CPU cooler works first off there's the CPU silicon which generates all of the heat the heat is conducted by the IHS or integrated heat spreader and from that point the IHS is communicating through a thermal compound between the IHS and the copper cold plates of your CPU cooler or aluminum in some cases that thermal compound is critical because it fills microscopic imperfections in the service of the IHS and the service of the cold plate for the CPU cooler without this compound the imperfections would be filled with air which has a much lower watts per meter Kelvin rating than thermal compound in fact it's about 0.02 4 watts per meter Kelvin for air whereas thermal compound is generally between 4 and 8 or so once the heat has been transferred to the cold plate the next key item is the heat pipes the heat pipes make contact with the cold plate and within the heat pipes is contained and evaporator believe it or not the heat pipes actually contain a liquid it's effectively a coolant and that is a composition of ammonium and ethanol or sometimes distilled water the liquid is heated up by the heat generated by the CPU and that creates a phase change this is critical to the process there's a ton of energy loss in the form of heat in a phase change and when that energy is lost it's because the liquid is now turning into a gas and so this gas starts traveling up the heat pipes at which point the heat pipes make contact with the aluminum fins these have a large surface area it's another key word here and the service area spreads the heat across the entire area of each effective layer within the aluminum fins the fins are then cooled by the cooling fan which pushes the heat off of them and out of the case so that the process can continue ad infinitum at this point in the process the gas makes it all the way to the top of the heat pipe at which point it is condensed and through capillary action it trickles its way back down to the bottom and repeats the process once the gas condenses back into a liquid the liquid trickles down the sides of the heat pipe normally made either centered groove or mesh we've copper grooved wicks run cleanly down the center of the tube and sintered wicks have a more porous and foamy look to them weave looks like a basket weave design and the high end air coolers will generally use a composite heat pipe instead which means it's a compound of multiple different designs so they use a copper powder which helps with thermal transfer and also helps with these steam movements so steam moves more quickly through the heat pipes composite and centered heat pipes cost more than grooved pipes but theoretically offer better performance and this feeds into the next point which is that material matters thermal conductivity or watts per meter Kelvin dictates the efficacy of cooler materials copper has a 401 watt per meter Kelvin thermal conductivity at 25 Celsius aluminum is 205 watts per meter Kelvin and then you've got your thermal compounds in your air after that we've tested and found that alloy and copper cold plates have minimal impact on cooling performance when using liquid coolers but haven't yet tested it with air coolers conductive heat transfer is expressed through 40 A's of law which is Q equals ka DT / s where a equals heat transfer area K equals the materials thermal conductivity s equals material thickness and DT is the temperature difference across the material or Delta service area and roughness also matter in this equation and larger CPUs like the LGA 2011 chips need a larger surface area cooler to contact all potential hotspots on the IHS using a cooler built for smaller CPUs like the silverstone AR 0 1 or hyper 212 will result in a poor edge performance on larger CPUs surface roughness should also be considered as it is needed to be as close to perfectly smooth as reasonably possible indirect contact is the result of rougher surfaces and that means a loss of full potential afforded by the copper and alloy materials which have the four hundred or 200 watt per meter Kelvin thermal conductivity measurements instead we end up relying more on thermal compound to bridge the gaps which is significantly lower in its quote unquote K rating than the metals and then there are vapor chambers vapor chambers help draw heat away from vrm coolers by hanging down from a chamber design similar to a heat pipe in some ways but they are better deployed for localized heat generation by high heat large areas like the VRM and the vrm coolers this helps spread heat more evenly across the fins as well so it's not just a BRM benefit and few devices use of vapor chambers but the ones that do the erratic we should dissipate that heat better across the service area and draw heat away more effectively from other non CPU components that neighbour the CPU so that's everything you need to know about the basics of CPU air coolers and how they work we'll do another video on liquid coolers and if you're interested in learning more about this topic you can hit the link the description below from my 2012 article I wrote on the same idea and it's got a bit more depth than you'll get here so if you do want that extra are part of the TLDR you can find that on the website as always thank you for watching if you like this content hit the patreon link post or video check us out on the channel for more videos and I'll see you all next time