Thermal Paste Removal

[peterb]

Certainly from experience in building AF amplifiers, using thermal compound does make a difference, and other posts in Hexus (and this subject does come up a lot!!) thermal compound does lower temperatures. Those that have lapped the heatsink and CPU report bettere thermal transfer although the trick there is getting the surface flat and smooth. Certainly two perfectly flat and smooth surfaces wouldn't need thermal compund at all, but you wouldn't need a heatsink clip either - if they were that smooth and flat, normal molecular attraction forces would hold the two together - achieving that degree of flatness and smoothness would be very difficult to achieve.

What difference does a dgree or two make? Certainly increasing the temperature will have a theoretical detrimental effect on electonic components, and as the technologies get smaller, the effects will become greater. In particular leakage current across semiconductor junctions will increase, so more heat will be generated etc. Systems that are periodically powered up and down will sufffer thermal shock and mechanical stress, and that will be greater if the end temperatures are higher. (Systems that are left running day after day will tend to be more reliable than those that are run up and shut down daily - that may not be true of electomechanical devices such as hard drives though)

So it is probably worthwhile lowering temperatures as much as possible. After all, the heat sinks supplied with CPU's have thermal compound on them - probably because it is cheaper than doing additional machining to get the surfaces smoother and flatter.

As for nail varnish remover - again not ideal as I think it contains stuff like lanolin to replace any oil;ds in the skin and nail, and these will be left as a residue on the heat sink/CPU surface.

[Salazaar]

Surely the question is not whether thermal compound makes a difference (of course it does!) or whether a degree or two is significant (depends on your opinion), but whether or not leaving that microscopic layer of residue from the TIM remover makes any significant difference to the thermal performance.

I've used the Akasa stuff a number of times on CPUs and GPUs now, all of which have been OC'd to some degree or other and none of which have suffered from any unusual thermal problems. I'd say it makes little or no difference, though I don't know whether the temps would drop by a degree or two if I did use IPA and I'm not sure I would have any good method of monitoring a tiny change like that anyway.

[ps3ud0]

Yeah, I understand the theory. But my point was, in practice, how much difference does it make?

For all intents and purposes null as I advised above - we are talking fractions of a degree really, perhaps measurable but unlikely to cause any issues.

Which was my point - in real-world terms, does it matter if there's thermal compound there at all, let alone a microscopic residue because it was cleaned with white spirit instead of IPA (etc)? I suspect that the cleaner makes little or no real-world difference, and I would be too sure about the thermal compound either.

I think thats been answered by peterb, but I would never recommend anyone not to apply TIM which would directly responsible for the higher temperatures since air is so thermally inefficient...

To get surfaces smooth enough to produce molecular bonding would be a technical engineering feat, which a normal consumer would never have access to. We are talking at the nanometre scale to produce such effects...

ps3ud0

[schmunk]

Is it about the right time to bring this venerable article into the discussion?

[Krumm]

I had no ipa the other day, so i just used meths and a toothbrush, which worked fine.

[cotswoldcs]

Nail Varnish remover... as I have some anyway (although it gets used a lot more for thermal paste than it does nail varnish)

That and some cotton buds. Job done.

I use (my wife's) nail varnish remover and read ages ago on another forum that it's OK to use. It's acetone free and cleans thermal goo off nicely. Main ingredients are ethyl acetate and isopropyl alcohol although it does list a ton of other stuff. I'm not sure whether any of the other stuff could do any harm?

What do you think? Safe to use or should I go for straight opropyl alcohol?

[Fraz]

Three pages on how to remove thermal paste...

[Salazaar]

Three pages on how to remove thermal paste...

This is important, damnit!

[Agent]

I use (my wife's) nail varnish remover and read ages ago on another forum that it's OK to use. It's acetone free and cleans thermal goo off nicely. Main ingredients are ethyl acetate and isopropyl alcohol although it does list a ton of other stuff. I'm not sure whether any of the other stuff could do any harm?

What do you think? Safe to use or should I go for straight opropyl alcohol?

Nail varnish remover is generally a no no as its too hard to decipher what the hell is in it. Many have a polish which can cause a film on the top of the processor (as mentioned in this thread), which may insulate heat, but more importantly, it can break down the thermal paste during its hot/cold cycles.

[Saracen]

....

I think thats been answered by peterb, but I would never recommend anyone not to apply TIM which would directly responsible for the higher temperatures since air is so thermally inefficient...

Not really it hasn't ..... and nor would I.

I don't disagree with anything peterb said, but it doesn't address the point I was making. Lapping is a completely different subject, as are AF (or RF) amplifiers, if for no other reason than than the nature of the heatsink is likely to be very different to a CPU cooler, as is the cooling, which is likely to be passive in most cases, rather than active.

For CPU coolers, though, my point was whether it made any real-world difference - by which I don't mean if it's measurable, but if it would change buying decisions if you knew. Are you going to fry the CPU if you use white spirit, or if you don't even use TIM? If you're not (and I'm aware of anecdotal evidence that suggests, at least with some of the older Athlons, fried chip is exactly what you risk), then how much temperature difference would it make, and what would be the implications of that? that is what I was getting at.

Is it about the right time to bring this venerable article into the discussion?

Now that was an interesting, and amusing read. I have to admire anyone who can write an article about thermal grease and manage to get the phrase "toasted toothpaste and Vegemite sandwich" into it!

From the article, though, and humour aside, the inferences I draw are, essentially, twofold :-

- provided you use a proper thermal compound (because other substances might work wonderfully short-term, but fail in the medium or long-term), it doesn't matter much what you use

- the difference between 'anything' (sensible, that is), and nothing, is fairly large (16C/W).

[peterb]

Hmm - I take your point Saracen - what is the effect of filling the gaps inbertween the contavt points between the heatsink and the CPU with the residue from the cleaner rather than air?

I had a look back through one og=f the (many!) previous posts about TIM/lapping/cooling and found this article

Heat Transfer

(I had posted it in anoy=there hread) which gives quite a good introduction to the basics of thermal management. The question really comes down to the thermal resistance of the residue filling the voids compared with that of the thermal compound used. The article sufggests that up to 90% of the contact area could be air (or whatever) so any reduction in the thermal resistance will be worthwhile. However it would be interesting to try it in practice!

Incidentally, whether the cooling is active or passive is largely irrelevant (in therms of the contact thermal resistance. That aspect is only to do with removing the heat from the heatsink - that is reducing the thermal resistance between the heatsink and the ambient surroundings. Forced air cooling will take the hot air away from the heatsink fins so the heat flow is higher, which in turn will increase the overall system efficiency, but it is still important to reduce the thermal resistance between the CPU and the heatsink base.

[Bluecube]

Another vote for nail polish remover despite what Agent says. I used it on my last few CPUs with no issues whatsoever. Think it was Clinique if you're interested I've also seen vodka recommended as well but never tried it myself.

[iranu]

I personally can't see how a very thin residue is going to cause a problem that will be noticed. Thickness of TIM will be probably be more important than residue.

I'd warn people to be careful with nail varnish remover because it contains acetone. It's fine to use but be careful not to spill it onto plastics.

It's been posted here before but thermal paste is not needed if both contact surfaces have been lapped to a high finish - vid on youtube was pretty cool. For most people paste is required and on that subject have you heard of the new diamond based thermal pastes? Petra's Tech Shop Supposed to be excellent. I've not found anywhere that sells it in the UK though.

There's also another invention that is supposed to surpass that too UB Materials Engineer Invents New Thermal Paste to Help Minimize Overheating in Electronic Devices - UB NewsCenter

[cotswoldcs]

I've also seen vodka recommended as well but never tried it myself.

I'd recommend drinking the vodka followed by some IPA and then it really won't matter what you use on the CPU - life will just feel that much happier that you won't care...

[iranu]

I'd recommend drinking the vodka followed by some IPA and then it really won't matter what you use on the CPU - life will just feel that much happier that you won't care...

Reminds my of the Ethanol Sunrises we had one christmas when I worked in a lab. And for god's sake kids don't try this at home because some alcohols will kill you even with tiny quantities if you get the wrong one.

[cotswoldcs]

Reminds my of the Ethanol Sunrises we had one christmas when I worked in a lab. And for god's sake kids don't try this at home because some alcohols will kill you even with tiny quantities if you get the wrong one.

That's why (if you followed my link) I was recommending Greene King IPA