Thermal pads for sticking heatsinks on VRM/VRAM, what thickness should I go for?

[crystal6tak]

Hey all!

Haven’t posted here for a looong time, please let me know if I did something wrong!

I’m wondering when using self-adhesive thermal pads to stick tiny heatsinks on VRAM/VRM on a graphics card, does the thickness matter? Normally the thickness is determined by the gap between the two object squishing against each other, but since I’m just sticking heat sinks on the PCB, what thickness thermal pads should I use then? 0.5mm? 1mm? 1.5mm?

Specifically, I have an EVGA 980 Ti FTW ACX 2.0 4996 and an Arctic Accelero Xtreme III I want to slap on. I’ll have to remove the front plate of the 980 Ti to install the Accelero cooler. Meaning it’ll reveal all the VRAM/VRM and what not that normally are cooled by the front plate. The thermal adhesive paste provided by Arctic creates pretty much a permanent bond between the PCB and the heatsink which I don’t want. I looked around and found the Alphacool Eisschicht self-adhering thermal pads 14 w/mK (17 too expensive) which I can buy at where I’m at. Problem is I don’t know whether to get the 0.5mm or 1mm variant.

Here’s a picture below showing the tiny silver heatsinks I want to stick on the VRM/VRAM

 

[Eximo]

I wouldn't call it permanent, a little wiggle with a pair of pliers and it comes off. Then you can scrub away the remaining paste.

Thinner is better, you just need to fill the gap, and since this is direct contact it actually doesn't matter.

 

[techgeek]

Normally you'd use the thickness needed to fill the gap between the heatsink and the VRAM / VRM's. However since you are replacing the stock single cool-all heatsink with a GPU + individual heatsinks, the thinner the pad the better. Even the best thermally conductive interface material will hinder cooling if it's too thick. The interface material is never going to be as thermally conductive as the heatsink itself, so the thinner the material is the less resistance the heat has to travel through getting to the heatsink.

 

[sharndowg]

Generally you want the smallest layer possible between heatsink and the component. If the layer gets too thick it can start to become quite inefficient at transferring heat.

Are you sure its a permanent adhesive? Do you see yourself reversing the cooler back in the future?

 

[Eximo]

Arctic labels it as permanent and fill their manual with all kinds of warnings. It is far from the most permanent thermal adhesive you can buy.

Were I at home I could take photos of a card that used to have an Arctic kit on it.

 

[crystal6tak]

Thanks for the quick responses!

I wouldn't call it permanent, a little wiggle with a pair of pliers and it comes off. Then you can scrub away the remaining paste.

Thinner is better, you just need to fill the gap, and since this is direct contact it actually doesn't matter.

Are you sure? Everywhere I read said they were permenant.

Generally you want the smallest layer possible between heatsink and the component. If the layer gets too thick it can start to become quite inefficient at transferring heat.

Are you sure its a permanent adhesive? Do you see yourself reversing the cooler back in the future?

The Accelero Xtreme III I got came with 1 tube of thermal adhesive rather than the two part thing. From what I read, this one isn't removable. (The two part one is) And yes, EVGA still covers warranty if I can revert the card back to it's stock state. So I definitely want to keep that as an option.

Normally you'd use the thickness needed to fill the gap between the heatsink and the VRAM / VRM's. However since you are replacing the stock single cool-all heatsink with a GPU + individual heatsinks, the thinner the pad the better. Even the best thermally conductive interface material will hinder cooling if it's too thick. The interface material is never going to be as thermally conductive as the heatsink itself, so the thinner the material is the less resistance the heat has to travel through getting to the heatsink.

I see, thank you!

 

[techgeek]

In my experience, any two part thermal compound is a thermal epoxy. Thermal epoxy is most definitely permanent, though sometimes you can get lucky and get it to shear without damaging the part underneath.

Usually one part compounds are just a grease which isn't permanent.

Is this kit new? Do you have a link to it?

 

[crystal6tak]

In my experience, any two part thermal compound is a thermal epoxy. Thermal epoxy is most definitely permanent, though sometimes you can get lucky and get it to shear without damaging the part underneath.

Usually one part compounds are just a grease which isn't permanent.

Is this kit new? Do you have a link to it?

Not new at all, there's a fourth version of it, I got the third version as it included the heatsinks. Anyways, here's the link. Even if it is removable, I heard they are a pain to remove, as they leave residue on the chips. In any case, I don't want to risk it.

Thanks for all the response! I'm going to go with the 0.5mm thermal pad. I'll leave this thread open for a few more hours in case anyone adds their 2 cents later. Then I'll pick a best answer (That's how this forum works now right? I have no idea).

 

[techgeek]

Sorry, I should have been more clear. When I said was it "new", I didn't mean the product itself, I meant did you buy it used? These heatsinks have been on the market for a long time.

Do you have links to the pads you are going to use? I purchased some thermal material for a similar project. The old pads were like a TIM filled fiber pad and they dried out / got hard and fell apart. I replaced them with a poly material (rubber like) because they don't dry out, shape well, etc. However if you remove them, they also leave a residue, because they are adhesive, it's the nature of the beast. Nothing to worry about a little isopropyl alcohol (99%) removes it easily.

 

[crystal6tak]

Sorry, I should have been more clear. When I said was it "new", I didn't mean the product itself, I meant did you buy it used? These heatsinks have been on the market for a long time.

Do you have links to the pads you are going to use? I purchased some thermal material for a similar project. The old pads were like a TIM filled fiber pad and they dried out / got hard and fell apart. I replaced them with a poly material (rubber like) because they don't dry out, shape well, etc. However if you remove them, they also leave a residue, because they are adhesive, it's the nature of the beast. Nothing to worry about a little isopropyl alcohol (99%) removes it easily.

Ah of course. Link to the Alphacool Eisschicht.
I got this Accelero Xtreme III brand new. As far as I'm aware, these alphacool pads are extremely high quality. The best I could find within 1 day of search. On paper at least.

I understand any type of adhesive will obviously leave residue, but from what I read it seems with the Arctic paste I have, I risk ripping of the chips if I try to remove it, while the thermal pad, which still leaves residue, is unlikely to rip the chips out. The most reliable source which says this paste is pretty much permanent is from here at the third paragraph. Looking at page 2, second picture, he received the same thermal adhesive as me. Then again, I'm very new at this. Only started researching today lol.

 

[techgeek]

Well it does say clearly that it is an adhesive. It must cure when exposed to air, though like I said all the ones I've used (I'm an Electronics Engineering Technologist) are two part compounds that cure when mixed.

Hopefully your pads will work with nothing pushing down on them. These are normally meant to be sandwiched between the component and heatsink which is held in place with screws. The pad I purchased (very similar to yours) had adhesive on both sides, but I'm not sure it would have supported the weight of an individual heatsink that didn't have some other mechanism holding it to the PCB. All I can say is once they are placed, put something (heavy) on the heatsinks to press them into the pad and leave it for a day or so. After that, then flip the card over so the heatsinks are down and hanging. This will test if the adhesive is holding. Unfortunately this won't test what happens once they've been warmed up. The adhesives grip could lessen once it's warm.

 

[crystal6tak]

Well it does say clearly that it is an adhesive. It must cure when exposed to air, though like I said all the ones I've used (I'm an Electronics Engineering Technologist) are two part compounds that cure when mixed.

Hopefully your pads will work with nothing pushing down on them. These are normally meant to be sandwiched between the component and heatsink which is held in place with screws. The pad I purchased (very similar to yours) had adhesive on both sides, but I'm not sure it would have supported the weight of an individual heatsink that didn't have some other mechanism holding it to the PCB. All I can say is once they are placed, put something (heavy) on the heatsinks to press them into the pad and leave it for a day or so. After that, then flip the card over so the heatsinks are down and hanging. This will test if the adhesive is holding. Unfortunately this won't test what happens once they've been warmed up. The adhesives grip could lessen once it's warm.

Thank you for all the help! I have ordered the alphacool eisschicht 14w/mk 0.5mm pads, let's hope this goes well. If it does, I might put up a guide on how to install the accelero xtreme iii on a 980 ti ftw as well as brief reviews for the pads, certainly haven't found one online yet.

 

[techgeek]

Well good luck, and certainly let us know how you made out.

 

[crystal6tak]

Well good luck, and certainly let us know how you made out.

So umm...I ordered some Sekisui 5760 thermal tape instead lol. Hopefully aquacooling approves the cancellation of my order on the alphacooling pads...