- Most thermal compounds
have a thermal conductivity of about 10 to 20 watts per meter kelvin, with really good ones reaching 30 or so. The king of all thermal compounds, liquid metal manages a whopping
73 watts per meter kelvin. But while browsing Newark,
an industrial supplier, we found this: The Panasonic
Pyrolytic Graphite sheet, or PGS, with an incredible
thermal conductivity of 1,950 watts per meter kelvin. But wait, that would make this thermal pad 20 times as conductive as liquid metal. Is that even possible? Can I do a 360 during this sponsor segue? Is that even possible? (Linus thuds)
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the video description. (upbeat music) - [Alex] Before we get started, I need to show you this because it's just absolutely amazing. - [Linus] Okay. - Just getting a little R and R, thinking about how my
circuit board over here can handle all this heat. - In fairness though, Pyrolytic Graphite really is a super cool substance, much cooler than that video. It's man-made and cannot
be found in nature, and while the actual process of fabricating Pyrolytic
Graphite is a bit over our heads. It sounds pretty sweet. Basically, you take a
hydrocarbon like methane and put it under a
vacuum of about one torr or about one 760th of
atmospheric pressure. Then you heat up the methane
to 2000 degrees celsius and slowly, about a thousandth
of an inch per hour, a layer of graphite grows. This creates perfect
hexagonal carbon sheets that lie on top of one another. What are they gonna think of next, right? The shape of the carbon crystals also makes Pyrolytic Graphite the most diamagnetic material by weight, meaning that it's repelled
by a magnetic field and can be levitated. Unfortunately, we don't have
a magnet big enough to try it, and we'd probably want a slightly
thicker sheet of graphite, but look, here's a cool video
of someone else doing it. Go check it out at the link below. This also makes it excellent
for electromagnetic shielding for use in things like
radio towers and satellites. Of course, we are not here
for the magnetic properties. You haven't even opened this, have you? - [Alex] No. - You have no idea if
this is going to work. - [Alex] Not at all. - We wanna look at its thermal properties. The most thermally conductive
substance in the world is a diamond with a thermal conductivity of around 2200 watts per meter kelvin. So we're getting very close here to the limits of thermal conductivity with that insane value of
1950 watts per meter kelvin. Apparently the thermal
conductivity of this stuff is so great that you can use a sheet of it to slice through an ice cube using just the heat of your hand.(beeps) It's this thin with an adhesive. - [Alex] So it's a 10
micrometer of graphite, and I think six micrometers of adhesive. - So how do I get this adhesive off? Like, I can't even get
a fingernail in there. Can you see it going in? What if we add more heat? Holy crap, it's actually
like going faster. I can tell like easily. I don't know if I have the
patience for the whole thing, but it definitely sliced into it. Check this out. And you can actually
tell it's sliced in more on the side that doesn't
have the adhesive on it. We really need to figure
out how to remove that. What if we scraped off a
corner of the graphite? Yeah, there, you can see
the plastic sheet there. Okay, I think I've got it peeled. There we go. Oh, my goodness, it's so thin. I think we're good. I think, I think I got it apart. - [Alex] Cool. - So this insane thermal
conductivity means that Pyrolytic Graphite
is used in, you know, blow stakes applications, like
the nose cones of missiles, rocket motors, nuclear reactors, and even heart valves of all things. But of course this is Linus Tech Tips. We wanna know if it's good
for cooling computers. Curiously, one of the
main selling points of PGS is its use in electronics, but it seems like the
marketing focuses on thicker, less thermally conductive
versions rather than the thinner much more thermally conductive
kind that I'm holding. This one is just 10 micrometers thick. Also curiously, it seems that
for the thicker thermal pads that Panasonic makes, they've
basically glued together a bunch of thin thermal pads with a thermally conductive glue. Now compared to other thermal pads, these offer excellent performance, but neither of those are gonna cut it if we wanna get the most performance. Ah, there it is, out of our CPU here. Before we test this out,
though, we need a baseline. Now we already pre-ran,
using Noctua's NT-H2, but there's already a graphite thermal pad on the market for computers. This is the innovation
cooling graphite thermal pad, and we looked at it a couple of years ago. It doesn't keep up with a
high quality thermal paste, but it's good enough. It's reusable. It creates no mess. It lasts basically forever, and it can withstand temperatures that your processor will never see. We actually really like this,
especially for test benches. One problem with the IC
graphite thermal pad though, is that it is electrically conductive. Apparently that is not
the case with PGS. (beeps) My scriptor says "From here, things get
loose and probably weird." Ah, that sounds about right. That is not a lot of resistance. Two ohms? - [Alex] Yeah, something like that. - Okay. Let's try this. Okay, that's very similar.
- [Alex] About the same. (Alex laughs) - With that out of the way, frankly, I have no idea what to expect now because already the spec sheet doesn't seem to be entirely forthcoming with real information about the product. And there's gotta be a reason that people aren't using this stuff. I have concerns about the thickness. - Yeah, that's my concern as well. - Like even just micro imperfections in the bottom of the heat sink or CPU seem like this isn't gonna bridge the gap. - Yeah, and there's stuff like, I think Noctua's thermal compound's not as thermally conductive
as a lot of other ones, but it works better because it's just better at spreading out and filling in those gaps. There's also like, think about how sick it would be to be able to just install one of these on the bottom of a cooler and just never worry about it again. - Yeah, wait, we don't know what the thermal conductivity
of that adhesive is though. - It's quite high. - [Linus] Oh, okay, there's
our innovation cooling pad. Now we can throw our NHD-14 on here. - [Alex] D15. - Is this a D15? - [Alex] Yep. - Well, there you go. - [Alex] It has your name on the box, and you don't even know what it is. - I'm more of a single tower cooler guy. - [Alex] But the Dualies are the best. - [Linus] Yeah, I know,
but they're so unwieldy. - [Alex] That's like part
of the appeal though. - Our test bench is a core i9 10900K, and we're running the
blender classroom test, which is gonna take us
about six or seven minutes, giving us a good idea of
where it's gonna top out. - [Alex] Yeah, for the NT-H2,
our average temperature was 86.4 degrees and the max was 90. So that's what we're going to be. I found this by just sorting
most thermally conductive on the website. And I was like, wow, that's really, really thermally conductive. (Alex giggles) - As expected, that's a little worse. So I'm doing some rough in head math, and I'm gonna say 93 and a half. - 93, not bad. - Yes. - That's worse, but it
didn't thermal throttle. - And that's all we really
need, 'cause that means we know that thermal output through the duration of
the test was the same. So we can shut it down now
and take a crack at this. - [Alex] I brought over a dowel pin, so that we can try and smooth it out. - Sure, that's actually
probably not a terrible idea. I mean this whole thing is kind of not really a great idea, but like-- - Should we adhere to the
heat sink or to the CPU? - I kind of liked your idea
of doing it to the heat sink. - Yeah, 'cause that would be so awesome to be able to just poop. - Plonk a heat sink on, yeah, okay. Once it sticks on there,
it's pretty sticky. So that's good for us to
know about right about now. Oh, lordy, okay. So here's the plan. (upbeat music) - [Alex] Like how it was
just here's the plan, and then nothing. - There is no plan. That's what I'm trying to say, Alex. (upbeat music) Good job, Linus. It looks like there's some
junk under there though. Doesn't it? (beeps) You know what, forget it. No, no, no, no, I'm out, I'm out. Try again. Oh, that's way better. I'm glad we didn't even bother to test the other application. If we discovered a
fantastic and affordable new thermal interface material, you can bet you'll find
it soon on lttstore.com, marked up, of course, - [Alex] Well, the
stuff is only like $7.50 for a sheet of it, like that size. - Wait, we spent $40 on this little pack? - Yeah. (beeps) - [Linus] If our idle temps
are anything to go by, this may actually work. Of course, idle temps tell
us not much of the story. - [Alex] We're also like just on the cusp of thermal throttling, which
is kind of unfortunate, but... - Well, that's fine because if it doesn't perform
as well as the IC pad, then it doesn't, it's irrelevant, so.
- [Alex] Yeah. - I don't think it's gonna work (Alex giggles) Not as well as this pitch
for lttstore.com anyway. All right. I want it to work 'cause
I want to be like, "Oh, we found a thing
that's so cool," but I, my hope level is quite low. (pops) And we're done bud. - [Alex] Oh, no. - And it's terrible. Oh, we dropped like 400
megahertz off our CPU. What if we put another layer on the CPU to try to, you know. Curiously the contact patch
actually isn't even that bad. - [Alex] It does only
contact this area here, but that's basically the dye. So that's kind of all that matters. - Well, it's about half. It's about half of the dye. the dye on the 10900K is
pretty big under there. You know what? I wanna try it. I wanna put another layer on the CPU. - Okay, screw it. How did you do it this last time? (beeps) - Good luck everybody. Oh, Oh, hi, hey, oh, yeah.
(Alex laughs) Got a fan going over there. (beeping) - That's, that's not great. - I kinda took out one of the pins here. If it doesn't do worse, I guess I can accept that
as sort of a small victory. F12 to pay respects. - [Alex] What, okay. (Alex laughs) - [Linus] Okay, so it's not
great for this application, but that's fine because
nobody advertised it as being great for this application. One of the other things
it is apparently good for is heat transport. So you might think, okay,
well, hey, Linus, okay, it's not that great for
moving heat from the CPU up to the heat sink, but what if it could spread it out a lot? Well, problem is that it's not nearly
as good as a heat pipe. Those can get up to a 100,000
watts per meter kelvin because they aren't
relying on just conduction. Instead they're using convection and phase change cooling together to move the heat around
like real quick styles. Some random other use cases for this stuff include apparently phones,
heated steering wheels, which I thought was pretty cool. That that would be a really neat way to kind of move the heat
around from the element to spread it out more evenly. Heated seats, again, to
spread heat out more evenly. Servers, very vague, but
apparently they're good for servers and radio antennas, which
we mentioned before. As for using it to cool
your computer, well, not unless you wanna run at, you know, 98 degrees cause you just
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and crazy cooling projects, why don't I, why don't we throw to the
five gigahertz laptop? - Sure, we do that all the time. - Yeah, check out the crazy, the crazy cooling the laptop with the blowing Metron server fan. Got it to five gigahertz,
that Alex and I did ages ago. You know, we could also throw people to another thing that didn't work. Like when we harvested the
thermal interface material from between Intel. - No, no, let's throw them to like the MacBook video. - How about all three?
Air bubbles and micro-nonconformities are going to be the biggest issues. Also, there's diminishing returns within thermal pastes and pads as they quickly become an insignificant part of the overall system's thermal resistance from CPU to atmosphere (the real heat sink).
They used EYGAXXXX01F graphite sheets which have great planar "ab-axis" conductivity (1950) but they don't mention perpendicular "c-axis" conductivity. I would also like to see them use pure graphite sheets without the adhesive layer for direct die cooling.
Would like to see this on direct die with a lapped cooler. Feel like that's the best shot at seeing what it's capable of.
As expected, performs worse than regular graphite pads and thermal paste.
I’m curious if lapping the CPU would’ve helped
What I was most interested in was him saying thermal paste is 10-20 wpmk and the best ones 30. Which ones are those? Kryonaut extreme is 14½ wpmk or so.
I want to see how a piece of aluminum foil with high mounting pressure compares to a lot of these pads. Still has 235 W/m.K, which is more than liquid metal. Is this whole "fill the gaps" thing actually true?
PGS is actually a capable product, and some variants of PGS are used for CPU heatsinks in industrial applications. LTT just didn’t do much research here, and actually seems to have used the wrong PGS product for this application.
This is a product that Panasonic wants to help you find the right fit for - they don’t intend for people to self-serve. It says so on their website. That’s how I recently chose a PGS product for a product I’m working on. I also recall the engineer mentioning that the adhesive-backed sheets are NRND if I’m not mistaken, so LTT just bought some discontinued PGS off the web thinking it might work (and was hoping to mark it up and sell it to his viewers).
These guys are in entertainment (and apparently fly-by-night accessory sales?), not engineering. So this review shouldn’t be taken as demonstrative of the performance PGS can achieve when properly specified and applied.
...is that an LG CX 48" they're using as a monitor but with a different (likely VESA) stand?