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Comment by spectramax | Hacker News Reader

I swapped PTIM (stock thermal paste) with Gallium alloy (Grizzly Conductonaut or Coolaboratories Liquid Metal). The results were absolutely incredible, better than what this article exemplifies. If you're going to open up the chassis, might as well go to the full extent and replace thermal paste with liquid gallium.

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I've always wondered why hardware manufacturers don't use better thermal paste on CPUs. When I build PCs I would always replace the stock thermal paste and the cost was always pretty minimal and that was without the economies of scale they'd have. If this small thing helps so much why wouldn't they use it? What is the down side?

Maybe because the lifetime of the computer will be shorter, hence, closer to the next sale?

What I've heard is that CPU manufacturers (intel specifically in this case) optimize for consistency over time - the crappy intel thermal paste will still be the same level of crappy in 10 years time but a lot of (much) more effective enthusiast stuff might degrade and stop performing as well before then.

Of course I don't remember where I heard this, nor do I have any sources...

> What is the down side?

The gain is low, it increases costs, and better thermal pastes are electrically conductive so applying them industrially is a more complex endeavour (as you absolutely can't risk leaking/spreading them to any component). The risk/reward just isn't there for manufacturers.

Do we have any better thermal paste in the work that provides better gain without being electrically conductive?

Or at least they last longer than 2 - 3 years?

Also any surface that comes into contact with the gallium should really be nickel plated.

Copper is OK, but Gallium does alloy slightly and you may need to reapply after a year or so, not a problem with nickel.

Gallium + aluminum = bad time so just be careful when doing so, all.

Yes agree but MacBook Pro heatsinks are copper.

Sure, but much of the rest of the machine is aluminum, so the caution is warranted. The two metals don't like each other. https://www.youtube.com/watch?v=IZkzxWZETds

The problem is that they like each other too much. Liquid Gallium basically soaks into the Aluminum, and the Gallium-Aluminum alloy is very weak, at least at room temperature.

Careful with liquid metal. Its conductive unlike normal thermal paste and can short things out if it gets out.

It cannot get out unless you overflow it with more than necessary.

Normal shock levels range in 2-5g maximums when you are carrying around your laptop in a briefcase, backback, by hand, etc. This is tested on a shaker table in the reliability lab at 10ms classical half-sine shock. They also do RMS, sine-burst, etc waveforms to ensure that the laptop is going to survive normal use.

The capillary action between gallium liquid sandwiched between the copper heatsink and the die is higher than any of the shocks or external forces you can experience in normal use. Higher by an order of magnitude. Also, the die surface has extremely high surface energy - it wants to wet badly.

It is not going to spill all over the motherboard.

UNLESS - 1) You apply more than necessary. 2) The heatsink is not secured correctly 3) During the application process, you spill all over the motherboard (what Linus @ Linus Tech Tips did in one of his videos).

There is literally no need to worry - I wish I can disclose where I work to give some credibility.

I read your first sentence and thought “boy do I have a Linus Tech Tips video for you”. But I read further and see that you have seen it :)

I have used liquid metal thermal compound before. It is not hard to apply correctly and works great.

Normal thermal paste is conductive also, including the AS5 that the author uses in the article. You can get electrically nonconductive paste too, but it's not as thermally conductive.

> Normal thermal paste is conductive also, including the AS5

The vast majority of thermal paste is non-conductive, including AS5.

Two things you need to do when applying LM.

Clear coat around the die covering any components (resistors and caps) and less is more. Seriously, a tiny drop is all you need.

Gallium also destroys aluminum, absorbs into copper (heatsinks), and conducts electricity making it easy to short out components... if I recall correctly.

It absorbs at an incredibly slow rate. If you’re going to apply it, you have to apply an extremely small amount so you’re not going to short anything out.

Most Apple spec intel CPUs have no die-side caps, you’re going to be fine.

How much do you use and how do you apply it? Is there no chance of it oozing out and causing havoc with the circuitry?

A lot of the premium thermal paste products are non-conductive (electrically) and still way better than the stuff they put on at the factory and will improve you situation.

I don’t think that thermal grizzly products are a bad place to start looking. I haven’t tried them myself, but GamersNexus are advertising/recommending them and I do trust them.

Is there no chance of that gallium alloy amalgamating with other metals it might encounter? It seems really sketchy, but I guess it's probably not since I've not heard horror stories.

Gallium eats aluminum like butter[0]:. Copper is safe, nickel plated copper is ok as well (might tarnish though)... solder joins are dead however.

One should be very careful if that stuff can leak.

[0]: https://www.youtube.com/watch?v=k919f7Qi4es&vl=en <--random video

> I haven’t tried them myself,

you should. kryonaut and conductonaut are both great. However I'd not recommend liquid metal (gallium) for daily use in a laptop with low tension force. I use liquid metal on delidded ones and kryounat elsewhere.

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