Difference between a compound, adhesive, and paste?

[Alexander Moore]

Just wondering what I need to be ordering. What's the most heat conductive? What's best for CPUs and GPUs, and what's best for the motherboard stuff?

I know my computer came with the greasy stuff for the CPU/GPU (AS5), and I've replaced that before myself, but for all the little chips and stuff there's those jelly-like pads of various colors on those.

I need to replace all of that. What would you suggest for each?

Once I figure out my terminology I'll use this article to aid my choice: http://www.tomshardware.com/reviews/thermal-paste-performance-benchmark,3616-11.html

Thanks!

PS: My heatsinks use screws to screw down onto the CPU and GPU... I dunno if I need something that really "sticks" or not, or if it would considered low pressure or high pressure or what. It's a laptop with copper heatsinks.

PPS: Why do we use pastes and such anyway? Wouldn't it make more sense to have a solid direct-contact between heatsink and the CPU/GPU? No middleman?

 

[hunter315]

None of them should be adhesives, they are sticky because they are gooey, not because they are glue. For the most part Thermal Compound and Thermal Paste are the same, its just a matter of preferred terminology.

The little chips are using thermal pads, it helps to fill the gaps between the chips and the heatsink so you can have a flatter bottomed heatsink and still cool those chips. The thicker the thermal pad the worse the cooling performance so most of those chips that are cooled by thermal pads aren't putting out a ton of heat.

For the thermal pads you can pick them up from frozen CPU pretty cheap
https://www.frozencpu.com/cat/l2/g8/c487/list/p1/Thermal_Interface-Thermal_Pads_Tape.html

People will tell you there is a world of difference between the pastes, there really isn't. Ignoring the liquid metal solutions there is only about a 3C difference between all the pastes in that tom's article, you can get a bigger difference by switching to a better fan.



The reason we use TIM(thermal interface material) is because air is awful at conducting heat, when you put metal on metal you think they are touching, in reality you'll probably only have about 20% of their surface area touching, the other 80% has to try to conduct heat through air. TIM fills those gaps so now you might have 20% touching with 70% going through a thin TIM layer which slows heat a little and only 10% having to go through a thick TIM layer or air. While this is still way worse than if you could get 100% metal-metal contact through welding them or the like, it is wayyyy better than having to try to conduct heat through air which actually serves as an insulator.

 

[Calculatron]

Pastes is kind of a weird, catch-all term. "Paste that on there," "That looks like a gooey paste," etcetera etcetera. It means anything from a type of glue, to a type of thicker liquidy mixture. I prefer to stay away from it.

Thermal compound, I believe, is the more proper terminology. (Could be wrong.) This just refers to the general mixture/composition of the material that you use for a thermal interface material.

Thermal Adhesives, as you can guess, are thermal compounds that you may glue things together with. The most popular use for this, for a CPU user, is if you're gluing passive heatsinks onto your GPU RAM modules.

As for why you need Thermal Interface Materials (TIM): http://www.tomshardware.com/reviews/thermal-paste-heat-sink-heat-spreader,3600-2.html

As for recommendations, I personally used Arctic Silver MX-4. It's always affordable and plentiful, and works great.

 

[Alexander Moore]

The reason we use TIM(thermal interface material) is because air is awful at conducting heat, when you put metal on metal you think they are touching, in reality you'll probably only have about 20% of their surface area touching, the other 80% has to try to conduct heat through air. TIM fills those gaps so now you might have 20% touching with 70% going through a thin TIM layer which slows heat a little and only 10% having to go through a thick TIM layer or air. While this is still way worse than if you could get 100% metal-metal contact through welding them or the like, it is wayyyy better than having to try to conduct heat through air which actually serves as an insulator.

Ah. I figured it'd be more contact than that is all. I understand there may be microscopic grooves or something, but I figured new processors and heatsinks are pretty perfectly smooth, so I thought contact between two perfectly smooth surfaces shouldn't have gaps.

And yeah, I kinda imagined just welding a heatsink to a CPU/GPU as well, but I figure we don't do that because it'd make maintenance a b*tch.

Well, I looked through that article I mentioned, and I feel interested in that liquid metal solution, but it sounds like I probably shouldn't and if I scratched-up my CPU/GPU to apply the stuff there may be no going back I suppose. So I think I'll go with the Gelid GC Extreme since apparently that made the top of thermal compounds. Sound like a plan?

I might try to coolaboratory liquid metal pad for the GPU (NVIDIA 580M).

I've been using Arctic Silver 5 up until now. Didn't know they were finally falling behind.

Edit: By the way, what do typical laptop mountings (likely what I have on this CLEVO chassis) classify as in "mounting pressure"? My laptop screws the heatsinks on and are upside-down during use.

I have to admit I'm really wanting to try the liquid metal, but I'm going to have to resist. I'm still a novice and yeah, I've applied AS5 a lot but I don't want to get full of myself and find myself dealing with more than I can handle. It sounds like it holds some slightly better results but the risk probably isn't worth it I suppose.

 

[Alexander Moore]

So what company would you say makes the best pads anyway? I need to replace the ones on my chipset because cat fur got all over it... ugh. I'd need quite a bit, and the article I linked to didn't really do pads besides Coolabratory Liquid Metal, which is kind-of a special case as it's not really supposed to stay in pad-form by what I can tell.

For the compound I think I'm gonna go with Gelid GC Extreme.

Please don't link me to US shops btw, I currently live in China. Finding it on TaoBao or Tmall would help me the most.

Really is a hassle though. I have a cat and live in China, so cat fur and particulate matter always builds up in my system very rapidly.