What is thermal interface
Thermal interface is a heat conductive medium used to more efficiently transfer heat from a CPU or chipset to a cooler such as a CPU Heatsink Fan cooler or a chipset heatsink. The thermal interface is placed between the CPU/chipset and the cooler.
Why do we need a thermal interface?
The simple reason is that the surfaces of both CPU cores, other chips, and coolers have uneven surfaces with many microscopic (and some not-so microscopic) imperfections. These small scratches and imperfections act as air gaps between the two surfaces. Now metal to metal heat transfer is pretty good, but air is a very inefficient heat conductor, and that's exactly what's trapped between the imperfections. A thermal interface "fills in" these air gaps and creates a larger area of contact between the two surfaces. Remember, in cooling, higher surface area equals better performance!
What Kinds of Thermal Interfaces are there?
We can break this down into 3 types:
- Thermal compound aka thermal goop, thermal paste: The best thermal interface
- Thermal pads: a foam pad with sticky surfaces on either side.
- Thermal putty: usually pre-placed on a heatsink. This is usually a yellow, putty like substance that is actually kind of hard to get off of your heatsink.
- Epoxy: like a thermal paste/goop except it also acts like a bond to superglue a heatsink to the CPU.
The best of the bunch is Thermal paste, which is further broken down into Silver based pastes and "other" pastes. In the past, silver based pastes had the highest performance because, surprise surprise, silver is a better heat conductor than the non-metal pastes. Silver pastes however, tend to have some electronic conductivity, which can wreak havoc on components because they can cause shorts in circuits. Of the silver pastes, Artic Silver III, OCZ Ultra II and Antec Reference Silver were some of the most popular. Now, there's a resurgence of super high performance ceramic based pastes that have no conductivity and yet have the same, or better performance to silver based compounds.
Ceramique, by the same company that makes the Artic Silver pastes, is currently all the rage and we recommend it as the paste of choice for enthusiasts.
However, reports are that Ceramique is has a super thick and gooey consistency and is very hard to work with, and OCZ's Ultra II is reputedly also low conductive or non-conductive altogether.
Avoid Thermal Pads and putty!
Thermal pads are pretty much the worst thermal interface possible. They are simply too thick and their heat conductive properties are really poor. They tend to be a favourite of OEMs and companies because they are easy to apply and cheap, and "they get the job done" as far as the companies are concerned. Many a videocard heatsink uses thermal pads as their interface, and you'll find many sites that have succesfully used a more efficient heat interface and improved the overclocking potential of a video card.
Thermal putty is not much better... it is a very poor heat conductor and is reallyonly used again because it's easy to apply.
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