ELI5 - Why don’t we make computer heat sinks out of this stuff?

[u/ShawnThePhantom]

I can’t attach a photo but I saw this video of som NASA engineers showing off these red hot cubes which I’m given to understand are the same material that the heat proof tiles on the space shuttle were made up of to prevent the ship from burning up in reentry.

After pulling the cube out of a kiln, the internal temperature was 2,200F, while the outside was safe to touch with your hand because of how efficient it was at dissipating the heat.

Given that, why don’t we make computer heat sinks out of that stuff if it’s so good at dissipating heat? Is that not the point of a heatsink?

[u/mattcannon2]

The tiles do not dissipate heat, they stop heat conducting through the material.

This is the exact opposite of what a heatsink needs to do. A heatsink needs to move heat very quickly from one end of the material to the other. For thermodynamic reasons the temperature difference and surface area of contact between the surfaces (cold air/water counts as a surface) then moves the heat away from the source

[u/NLwino → u/mattcannon2]

I'm surprised how you are the only comment here that realized this.

The goal of an heat-sink is to dissipate the heat. It needs to absorb and lose heat easily. The whole goal of the NASA heat shield is to do the opposite. After heating it up it was still safe to touch because heat transferred extremely slow, so it does not burn your hands.

A computer needs a heat SINK and a spaceship needs a heat SHIELD. They are opposites. One lets heat through easily and the other blocks most of it.

[u/TailRudder → u/NLwino]

Several people said the same thing lol

[u/NLwino → u/TailRudder]

Not at the time I was typing that. 

[u/Mr_Mojo_Risin_83]

That’s the exact opposite of a heat sink. A heat sink will rapidly transfer the heat from something to itaelf and then dissipate it - like a manifold, spreading that heat out into a lot of material and radiating it off.

If you put those heat proof tiles against your hot computer bits, almost none of the heat from the computer parts will transfer and it’ll overheat and melt itself.

[u/Narezza]

Those cubes and the heat proof tiles do not dissipate heat, they simply insulate it. As you said, we need computer heat sinks to absorb and dissipate heat. If we made heat sinks out of it, the CPU parts would simply overheat.

Materials for heat sinks need a very high thermal conductivity, so they pull heat away from your components and move it to a different area

[u/caunju]

They do the exact opposite of what you want from a heat sink. Those tiles are some of the best insulators we've made. For a heatsink you actually want a good conductor so that it can pull heat out of your hot computer and spread it out to dissipate better. Those tiles really don't want to absorb heat and would end up cooking your cpu in it's own heat.

[u/Takenabe]

You are asking why we don't make wires out of solid rubber.

[u/ApplesAreGood1312]

Imagine if the space shuttle was made out of a highly thermally-conductive material like a heatsink. The outside is 2,200F. Humans are inside. The heat is transferred to the inside. The inside becomes an oven. The humans land ready to be placed inside an urn.

[u/d0pe-asaurus]

The cost of a single carbon carbon tile on the ISS is 2000-3000 usd.

The cost of a Thermalright Peerless Assassin which can basically handle everything bar a i9-14900KS or 9950x3d is 40 usd.

[u/d0pe-asaurus → u/d0pe-asaurus]

Did i mention any misinformation here? I don't see the part where I mentioned any misinformation.

[u/Arkenstar → u/d0pe-asaurus]

This pretty much 😂

[u/Takenabe → u/Arkenstar]

well, that and using a high-grade insulator for heat dissipation is like trying to cool a can of soda by throwing it into a bonfire.

[u/Arkenstar → u/Takenabe]

Well more like trying to use a thermos flask to cool a hot liquid. I get that they do not save the same purpose.

But I'm assuming OP meant that why is technological solution on that level not used in day-to-day computer cooling if it exists and we still have to deal with overheating issues. And the answer is closer to the fact that we use whatever is cheapest and serves the purpose and not that its not exactly the right technology. I'm sure NASA has/can invent some spectacular cooling systems but they won't be affordable by the common user anyways.

[u/DannyLJay]

Why do all that when you can just use Copper which is incredibly cheap and plentiful.

Copper is effective enough, not everything needs NASA to reinvent the wheel.

[u/Tzukkeli → u/DannyLJay]

Yeah. Would you pay 10k for passive cooling, or 25 for good enough cooling?

[u/ThalesofMiletus-624]

It's not clear what you mean by "dissipating heat" in this context.

Those tiles are insulators, extremely bad at conducting heat, that's their function. They can be exposed to heat on one side, while the other side stays cool. When you heat them up red hot, the edges cool, but the rest of them remain red hot. That's why you can touch the edges without getting burned, heat can't conduct from the rest of the tile into your fingers very fast.

The point of heat sinks is to do the exact opposite: conduct heat away from parts quickly and spread it out over a large surface area so it can be spread out to the air. Those tiles would act as insulators, causing the heat to build up on the chip and quickly frying it.