We've all been using thermal paste for years and decades. While there have been small continuous improvements, the basic concept has always remained the same. You apply a paste between hot chip surface and cooling solution, to fill in the microscopic cracks between both surfaces, improving heat transfer. Thermal Grizzly KryoSheet comes with a slightly different approach. It's a pre-cut thermal pad that can be handled in one piece, doesn't have to spread out over the surface and is completely dry, which means it will not dry out over time.

According to Thermal Grizzly, the material used is "a graphene thermal pad," with "a molecular structure stacked in the Z-direction," "in which the hexagonal crystal structure of the graphite is broken up along the basal plane." While I think that's a legally valid description for something called "graphene," the pad is not the textbook definition of graphene, which is a single layer of carbon atoms arranged in a perfect honeycomb pattern. Rather, it seems the pad is a mix of various components, one of which is carbon flakes of a certain size, which enables the use of the word "graphene." The original technology was invented by Smart High Tech AB in Sweden, who offer such pads for many other applications, too. Their descripton is "high-performance graphene-reinforced material." Just like many other nanomaterials, a pure graphene sheet could be toxic because tiny particles could break off and enter your skin or lungs and end up trapped like asbestos. That's why consumer-grade graphene is expected to always be embedded in some binding material. While I couldn't find anything on health safety at either manufacturer website, I think it's safe to assume that the material is safe to handle for consumers, or the product wouldn't be available for sale to end-users. At the end of the day the material used isn't the focus, because what matters is whether cooling performance is good and if the product is easy to handle.

Classic thermal pastes will dry out over the years, which lowers their cooling performance. While the effect varies between the actual pastes used, it's something many people are worried about when building PCs that will see very little maintenance. If you upgrade your system every year, or mess with your watercooling loop all the time, then this is completely irrelevant for you of course. A similar, secondary phenomenon is called "pump out," due to the thermal expansion of the various materials. When the heatsink and GPU chip heat up, they will expand slightly, which puts pressure on the thermal interface material. If that is runny enough, a tiny amount will get squished out the sides during every heat cycle, causing a loss of TIM in the cooled area and resulting in slightly increased temperatures.

Due to its design, the KryoSheet will avoid both these effects, it's completely dry, yet not brittle. It's easy to handle using tools or with your fingers—you still should treat it reasonably carefully, it's not unbreakable. Compared to thermal paste I found the application easier, because you don't have to spread anything out in a thin layer. The KryoSheet is not your standard thermal pad (like you know from memory chips or SSDs), it's just 0.2 mm thin, roughly twice as thick as a piece of paper, which is a good compromise between making it as thin as possible and ensuring stability—you still need to be able to handle it without breaking. The sheet comes in predefined sizes, which means you usually have to trim away some excess. Due to its electrically conductive nature it's essential to ensure you do not short out anything, like capacitors on the surrounding chip substrate. For me that was the biggest challenge. While it's easy to tackle, it is something you must be aware of, unlike thermal paste which is usually not conductive, requiring less care during application. Cutting the KryoSheet is easily done with some scissors, I found it best to leave a little bit of extra space on the sides, also to account for any possible movement of the sheet.

This brings us to the second thing to point out for installation. The pad is very light-weight and since it's dry, it will not stick to any surfaces. With a thermal paste you can just shake and flip everything around and the paste will not move—this makes assembly easier. With the KryoSheet you have to make absolutely sure that it stays in-place, otherwise there could be a lack of contact, or even short circuits. I found it best to put the pad on the chip (turn off your AC to eliminate airflow in the room) and then do a dry run how to place the cooler. This lets you figure out the best positioning, how to hold the cooler, and you can memorize the location of the mounting holes. Then lift it up again, inspect for any movement and then put everything together. It's not terribly difficult, but it is more complex than with a thermal paste. The drawback of thermal paste on the other hand is that you need to make sure you apply a thin, even, layer of paste. While this is pretty easy with MX4, modern high-performance pastes like MX6 are much harder to spread evenly, which almost makes this a selling point for the KryoSheet.

I have to admit, in terms of cooling performance I'm positively surprised. Before my own testing I expected "a bit worse," "similar," maybe "close enough" temperatures, but the actual results confirm that the KryoSheet offers (slightly) better performance than thermal paste. I tested Arctic MX4, an affordable, widely available, easy to spread paste, MX6, which is higher performance, but more expensive and more difficult to apply. Also included in the test group is Thermal Grizzly's own Kryonaut paste, which I found even slightly harder to apply than MX6. I intentionally did not include Liquid Metal in this testing, because it's quite difficult to fully remove, which could have affected other test results. Especially the KryoSheet could theoretically benefit from some sort of microscopic filler on the die from previous testing that wasn't fully removed. While I don't have any numbers to back up my claim, I think we can all agree that Liquid Metal will give you slightly lower temperatures, but it comes with its own list of drawbacks.

Looking at GPU temperature I'd say that all materials tested, including KryoSheet perform virtually identically. A difference of 1-3°C really doesn't matter much, unless you're trying to break records. Even for overclocking I wouldn't bet my system stability on a 3°C difference, because that might disappear in summer months, when your AC is off, or when a long gaming session heats up your room. While the temperature results for "hotspot" are similar, they do show a little bit of a bigger spread, up to 5°C, which is starting to become significant, at least for a high-end graphics card. For lower-end cards that run pretty cool anyway, there is no functional difference between 75°C and 80°C, for example, other than the number in monitoring software. Silicon lifetime isn't affected enough by such a small difference, and I think statistically the chances of you breaking the product while applying thermal paste are higher than just letting it run untouched. On the other hand, as mentioned before, after many years, thermal pastes have a tendency to dry out, so replacing thermal paste once during the lifetime of the product does make sense. Using KryoSheet could save you that step, because it won't degrade over time.

Priced at between $20 and $30 for a single sheet, the KryoSheet is not cheap, especially considering that it's single-use. I guess you could reuse it between mountings on the same chip if you're careful, and it's probably possible to cut a used pad to smaller size, for a smaller chip, but it's definitely not like thermal paste where a single tube can be used for a dozen applications. For most users this is a non-issue, because they don't need that many mountings in a short time anyway, and a few-year old, dried up, tube of thermal paste isn't helpful either. I still find hard to justify spending that amount of money to save a few degrees and for peace of mind regarding drying out of paste. If Thermal Grizzly could bring their price much closer to $10, or offer packages with multiple, larger sheets, then things could become interesting for a vast majority of the market. If they manage to make it non-conductive, then it could become an even bigger hit, because that's what most people seem to be scared of. Overall I'm positively surprised by Thermal Grizzly KryoSheet, it's definitely a useful alternative to the various thermal pastes on the market.