Ridge
June 6th, 2005, 23:17
By hey_moe
There are many things to consider when planning cooling systems. It is my hope that this article will help to make some of those decisions easier. I will talk about case cooling, component cooling, and CPU cooling and various methods of doing each.
CPU air cooling
Today?s CPUs with higher MHz and voltages generate much more thermal loads than they used to; if you overclock with more voltage your are generating even more and the heatsink and fan become more important.
There are many different types and sizes as well as metals used to make heatsinks The most common metals used are aluminum and copper. These metals are used due to their thermal efficiency or their ability to transfer heat quickly. While both metals transfer heat well , copper has better thermal efficiency , but can be bent easily drastically reducing its efficiency ; also it is more expensive. This is often why you see heatsinks made of aluminum fins and or a copper base.
In general , the copper heatsink will be the best way to go for performance. It should be handled with care in order not to bend the fins. The core or base of a heatsink of good quality should have a very polished base surface. This means that the surface has been polished to minimize the surface imperfections therefore having better thermal transfer between the CPU die and the heatsink. (More on this later).
The fins are designed to give maximum surface area for the most efficient heat transfer from the heatsink core to the ambient air. Some of the newer heatsinks are now using heat pipes in combination with fins to more rapidly channel the heat from the core and quickly disburse the heat evenly over the fins. With these larger, heavier heat sinks the use of the mounting holes on the motherboard are the preferred method for securing the heatsink instead of using the clips on the CPU socket. For some who have not mounted a heatsink using this method the task may look a bit intimidating however this is really quite simple, and the instructions are easy to follow in most cases. Some heatsinks come with fans and some do not. If you have a great heatsink and get a cheap fan it would be counter productive.
There are certain things to look for in a good fan - the amount of air it moves (cfm), the noise it makes (db), and that it has good dual bearings. Normally the lager fans like the 92mm will move more air than say a 60mm or 80mm fan. The better the cfm rating , the better performance and higher db rating in most cases. This is why a fan controller is very nice to have..the fan speed can be reduced when maximum cooling is not needed , keeping it a bit quieter or increased for maximum cooling when needed. Generally speaking , the stock heat sink and fan are just good enough for a stock CPU at normal ambient heat conditions.
There are others out there but this will give you an idea of what I feel is high quality.
Thermal compounds
Thermal compounds are very important. because microscopic imperfections are in the surfaces of even the best manufactured heatsinks and CPUs. These imperfections will hold air causing less than perfect heat transfer from one medium to the other. Thermal compounds should fill these microscopic imperfections, effectively squeezing almost all the air out from between the contact surfaces. This being said, the thinner you can keep the thermal joint, the better. It is bad enough we have to transfer between different barriers- if the thermal paste is applied too thick, it becomes more like insulation, and will not transfer heat effectively.
I feel the best of the thermal compounds are made by Arctic Silver. Arctic silver 5 is the best for air and water cooling solutions. Care must be taken as Arctic 5 can be conductive and should not get on any electrical circuits. The instructions for this product are located here: http://www.arcticsilver.com/ (http://www.arcticsilver.com/)
For phase change cooling I would suggest arctic silver Ceramique as it holds better at extreme cold temperatures
Case cooling
To keep the components and CPU cool , the case must get cool outside air circulating well in the case.
This is done with case fans. There is really no limit to what you can do here. I would suggest at a minimum three 80mm fans be used; one at the front blowing in to the case, one at the rear of the case blowing out, and one in the side panel blowing in to the CPU. A lot of people use duct work to duct cool air directly from the side panel fan to the CPU. Others will also cut a hole on the top of the case to blow out more hot air.
As I stated there are many things you can do; the goal is to have good cool outside air circulatinmg thoughout the case because this air is used to cool not only the CPU, but the chipset, memory, mosfets, and video card.
Also it is a good idea that all the fans are getting power from the power supply directly and not from the motherboard fan headers. One thing to remember is that with moving air comes dust. There are a couple of things you can do. One is to blow out the computer with air to clean every couple of weeks or two use fan filters. There are a few on the market and they do save you from the bi weekly cleaning.
The extra touch
The use of small a fan can be used to cool the memory. This can help while overclocking and will help you get that last bit of FSB. There are active memory coolers on the market like Thermaltake or as I prefer to do, you can make your own by attaching a fan to the existing memory heat spreaders using silicon or arctic adhesive. Also getting a heat sink on the southbridge is a good idea. I find the Zalmon heat sink to be very good for this, however here to you can make your own out of an old heat sink. In order to attach them I use Arctic silver thermal adhesive or Arctic aluminum thermal adhesive. Once again the difference is the aluminum is nonconductive and is a bit safer to use while still having great thermal qualities.
The use of small heatsinks or ramsinks on small chips such as frequency generators (PLL), power supply regulators (MOSFET) will keep these hot components cool allowing for good voltage regulation while overclocking. Something that works well if not better for the mosfets is to take an old aluminum CPU heatsink and cut it up to make ramsinks and attach them with arctic thermal adhesive. As for the northbridge there are better cooling solutions for it as well ,.from better heatsinks to water cooling. If you are going to keep the stock heatsink for the northbridge, make sure to check that there is a good coating of thermal compound under the cooler ; I would suggest the use of Arctic 5 thermal compound. If any of the rest of you guys wanna add a few more idea's please feel free, thanks Mike:wavey:
There are many things to consider when planning cooling systems. It is my hope that this article will help to make some of those decisions easier. I will talk about case cooling, component cooling, and CPU cooling and various methods of doing each.
CPU air cooling
Today?s CPUs with higher MHz and voltages generate much more thermal loads than they used to; if you overclock with more voltage your are generating even more and the heatsink and fan become more important.
There are many different types and sizes as well as metals used to make heatsinks The most common metals used are aluminum and copper. These metals are used due to their thermal efficiency or their ability to transfer heat quickly. While both metals transfer heat well , copper has better thermal efficiency , but can be bent easily drastically reducing its efficiency ; also it is more expensive. This is often why you see heatsinks made of aluminum fins and or a copper base.
In general , the copper heatsink will be the best way to go for performance. It should be handled with care in order not to bend the fins. The core or base of a heatsink of good quality should have a very polished base surface. This means that the surface has been polished to minimize the surface imperfections therefore having better thermal transfer between the CPU die and the heatsink. (More on this later).
The fins are designed to give maximum surface area for the most efficient heat transfer from the heatsink core to the ambient air. Some of the newer heatsinks are now using heat pipes in combination with fins to more rapidly channel the heat from the core and quickly disburse the heat evenly over the fins. With these larger, heavier heat sinks the use of the mounting holes on the motherboard are the preferred method for securing the heatsink instead of using the clips on the CPU socket. For some who have not mounted a heatsink using this method the task may look a bit intimidating however this is really quite simple, and the instructions are easy to follow in most cases. Some heatsinks come with fans and some do not. If you have a great heatsink and get a cheap fan it would be counter productive.
There are certain things to look for in a good fan - the amount of air it moves (cfm), the noise it makes (db), and that it has good dual bearings. Normally the lager fans like the 92mm will move more air than say a 60mm or 80mm fan. The better the cfm rating , the better performance and higher db rating in most cases. This is why a fan controller is very nice to have..the fan speed can be reduced when maximum cooling is not needed , keeping it a bit quieter or increased for maximum cooling when needed. Generally speaking , the stock heat sink and fan are just good enough for a stock CPU at normal ambient heat conditions.
There are others out there but this will give you an idea of what I feel is high quality.
Thermal compounds
Thermal compounds are very important. because microscopic imperfections are in the surfaces of even the best manufactured heatsinks and CPUs. These imperfections will hold air causing less than perfect heat transfer from one medium to the other. Thermal compounds should fill these microscopic imperfections, effectively squeezing almost all the air out from between the contact surfaces. This being said, the thinner you can keep the thermal joint, the better. It is bad enough we have to transfer between different barriers- if the thermal paste is applied too thick, it becomes more like insulation, and will not transfer heat effectively.
I feel the best of the thermal compounds are made by Arctic Silver. Arctic silver 5 is the best for air and water cooling solutions. Care must be taken as Arctic 5 can be conductive and should not get on any electrical circuits. The instructions for this product are located here: http://www.arcticsilver.com/ (http://www.arcticsilver.com/)
For phase change cooling I would suggest arctic silver Ceramique as it holds better at extreme cold temperatures
Case cooling
To keep the components and CPU cool , the case must get cool outside air circulating well in the case.
This is done with case fans. There is really no limit to what you can do here. I would suggest at a minimum three 80mm fans be used; one at the front blowing in to the case, one at the rear of the case blowing out, and one in the side panel blowing in to the CPU. A lot of people use duct work to duct cool air directly from the side panel fan to the CPU. Others will also cut a hole on the top of the case to blow out more hot air.
As I stated there are many things you can do; the goal is to have good cool outside air circulatinmg thoughout the case because this air is used to cool not only the CPU, but the chipset, memory, mosfets, and video card.
Also it is a good idea that all the fans are getting power from the power supply directly and not from the motherboard fan headers. One thing to remember is that with moving air comes dust. There are a couple of things you can do. One is to blow out the computer with air to clean every couple of weeks or two use fan filters. There are a few on the market and they do save you from the bi weekly cleaning.
The extra touch
The use of small a fan can be used to cool the memory. This can help while overclocking and will help you get that last bit of FSB. There are active memory coolers on the market like Thermaltake or as I prefer to do, you can make your own by attaching a fan to the existing memory heat spreaders using silicon or arctic adhesive. Also getting a heat sink on the southbridge is a good idea. I find the Zalmon heat sink to be very good for this, however here to you can make your own out of an old heat sink. In order to attach them I use Arctic silver thermal adhesive or Arctic aluminum thermal adhesive. Once again the difference is the aluminum is nonconductive and is a bit safer to use while still having great thermal qualities.
The use of small heatsinks or ramsinks on small chips such as frequency generators (PLL), power supply regulators (MOSFET) will keep these hot components cool allowing for good voltage regulation while overclocking. Something that works well if not better for the mosfets is to take an old aluminum CPU heatsink and cut it up to make ramsinks and attach them with arctic thermal adhesive. As for the northbridge there are better cooling solutions for it as well ,.from better heatsinks to water cooling. If you are going to keep the stock heatsink for the northbridge, make sure to check that there is a good coating of thermal compound under the cooler ; I would suggest the use of Arctic 5 thermal compound. If any of the rest of you guys wanna add a few more idea's please feel free, thanks Mike:wavey: