Gettin greasy ...
Thermal grease, thermal paste, thermal gel, heat sink goop, heat transfer compound, thermal interface material - whatever you prefer to call it, the names and substances differ but the function and purpose is always the same.
I suspect that most people here at TBCS are well aware of the importance of cooling their PCs and the critical role thermal grease plays.
An introductory summary of thermal grease basics:
Thermal grease (by any name) is placed between very hot components and a heatsink; its purpose is to maximize efficient heat transfer between the part and the heatsink. Without it, even the mightiest heat sink will become inefficient (the gap would be filled with air, which is a terrible thermal conductor), leading to the part overheating and failing.
Failure on PC parts failure is often expensive, quick, dramatic, catastrophic, and permanent. A lot of electrical power flows through a lot of very dense circuitry and generates a lot of waste heat, if this heat isn't removed from chip's tiny surface area, it will zorch in seconds - literally exploding into a little blast crater filled with fused silicon slag. This explosion can sometimes blast a hole through the socket and smoke the entire motherboard.
Don't believe the hype? Check some videos here, here, and here. Note that Intel or AMD, ATI or nVidia, no brand is immune and no manufacturer should be trusted - all complex large chips can and do get this hot (CPUs, GPUs, and "Northbridge" MCHs in particular). Overclocking will run them even hotter.
Almost every cooling system that exists involves some kind of heatsink or mechanism that takes the heat from one place and gets rid of it somewhere else. Virtually every one of these requires direct contact between the heatsink and the hot part and thus uses some form of thermal interface material.
Now, to the point ...
As I understand it, most of thermal grease products use some kind of sticky, greasy binder in which microscopic particles of some other substance (the efficient thermal conductor) are suspended. Countless formulations exist.
The binder is usually some kind of silicon gel, but manufacturers often cut corners by diluting with petroleums, plastics, and mineral oils. (This practice usually reduces final efficiency a little while making the manufacturing process a lot easier and cheaper. The consumer might cry foul, but remember, the alternative is paying substantially more and getting fewer choices on products that aren't significantly better.)
The suspended thermal conductor is typically
- ceramic oxide (cheapest and by far the most common)
- metallic oxide (higher cost and efficiency; typically aluminum, copper, or silver, sometimes gold)
- carbon (extreme cost and efficiency; can be graphite, diamond, fibers or filaments)
Wikipedia's Thermal Paste article generally agrees with what I've learned, but it also includes mention of liquid metals (gallium, mercury, cadmium etc) while I personally consider them to be more of an exotic category of their own; they tend to be so expensive and toxic that I doubt many consumers will ever see one.
The chemistry of the thermal paste (especially the type and concentration of the main ingredient) fundamentally determines how well it works. Brand doesn't matter, price doesn't matter.
Everyone already knows (or should know!) that thermal grease is absolutely required and any kind of thermal grease is infinitely better than none at all. To put it into perspective, even crappy cheap alumina-based thermal grease will transfer over 8000 times more heat than the same volume of air.
Avid overclockers and gamers automatically recognize certain premium brands (like Arctic Silver 5). Most authorities agree that silver-based pastes are superior, though the measured temp improvements are very small (and sometimes even disputable, since the measured ranges often fall with the error margin built into most PC temp monitoring systems). Although I agree that Arctic Silver is a fine product, I feel that brand isn't important and any silver-based thermal paste should perform nearly identically. Of course, not all brands are created equal, so (like the linky says) buyer beware.
Most (if not all) OEMs and vendors ship their products with cheap bulk-discount thermal grease; it's generally good enough to keep the computer or computer part running *at rated specifications* until the return-period or warranty expires. After that, it's the consumer's problem, not the vendor's. I routinely clean this cheap junk off and apply a better (silver-based) grease whenever I obtain a new part, just to be sure. As a bonus, I can verify the actual part numbers on the exposed chip and install a thermal probe while I'm at it. Part numbers never lie (well, it's easier to determine if they're lying, while it's impossible to get the real truth from clever software.)
Reply With Quote
Originally Posted by Larry Johnson
