After our launch-day investigation into delidding the 9900K and finding its shortcomings, we’ve been working on a follow-up involving lapping the inside of the IHS and applying liquid metal to close the story on improvement potential with the delid process. We’re also returning to bring everyone back to reality on delidding the 9900K, because it’s not as easy as it may look from what you’re seeing online.
We already know that it’s possible to see performance improvement, based on our previous content and Roman’s own testing, but we’ve also said that Intel’s solder is an improvement over its previous Dow Corning paste. Considering that, in our testing, high-end Hydronaut paste performs nearing the solder, that’s good news when compared to the older thermal compound. Intel also needed to make that change for more thermal headroom, so everyone benefits – but it is possible to outperform it.
Alongside the question of how frequently liquid metal should be replaced, one of the most common liquid metal-related questions pertains to how safe it is to use with different metals. This includes whether liquid metal is safe to use with bare copper, like you’d find in a laptop, or aluminum, and also includes the staining effect of liquid metal on nickel-plated copper (like on an IHS). This content explores the electromechanical interactions of liquid metal with the three most common heatsink materials, and does so using Thermal Grizzly’s Conductonaut liquid metal. Conductonaut is among the most prevalent on the market, but other options are made of similar compound, like Coollaboratory’s Liquid Ultra.
Conductonaut is a eutectic alloy – it is a mix of gallium, indium, and tin. This is Galinstan, but the individual mixtures of liquid metal have different percentages for each element. We don’t know the exact mixture of Conductonaut, but we do know that it uses gallium, indium, and tin. Most liquid metals use this mixture, just with varying percentages of each element. Gallium typically comprises the majority of the mixture.
“How frequently should I replace liquid metal?” is one of the most common questions we get. Liquid metal is applied between the CPU die and IHS to improve thermal conductivity from the silicon, but there hasn’t been much long-term testing on liquid metal endurance versus age. Cracking and drying are some of the most common concerns, leading users to wonder whether liquid metal performance will fall off a cliff at some point. One of our test benches has been running thermal endurance cycling tests for the last year now, since September of 2017, just to see if it’s aged at all.
This is a case study. We are testing with a sample size of one, so consider it an experiment and case study over an all-encompassing test. It is difficult to conduct long-term endurance tests with multiple samples, and would require dozens (or more) of identical systems to really build-out a large database. From that angle, again, please keep in mind that this is a case study of one test bench, with one brand of liquid metal.
Tripping VRM overtemperature isn’t something we do too often, but it happened when working on Bitwit Kyle’s 7980XE. We’re working on a “collab” with Kyle, as the cool kids call it, and delidded an i9-7980XE for Kyle’s upcoming $10,000 PC build. The delidded CPU underwent myriad thermal and power tests, including similar testing to our previous i9-7980XE delid & 7900X “thermal issues” content pieces. We also benchmarked sealant vs. no sealant (silicone adhesive vs. nothing), as all of our previous tests have been conducted without resealing the delidded CPUs – we just rest the IHS atop the CPU, then clamp it under the socket. For Kyle’s CPU, we’re going to be shipping it across the States, so that means it needs to not leak liquid metal everywhere. Part of this is resolved with nail polish on the SMDs, but the sealant – supposing no major thermal detriment – should also help.
Tripping overtemperature is probably the most unexpected side of our journey on this project. We figured we’d publish some data to demonstrate an overtemperature trip, and what happens when the VRMs exceed safe thermals, but the CPU is technically still under TjMax.
Let’s start with the VRM stuff first: This is a complete sideshoot discussion. We might expand it into a separate content piece with more testing, but we wanted to talk through some of the basics first. This is primarily observational data, at this point, though it was logged.
Running through the entire Skylake X lineup with TIM vs. liquid metal benchmarking means we’ve picked-up some very product-specific experience. Skylake X has a unique substrate composition wherein the upper substrate houses the silicon and some SMDs, with the lower substrate hosting the pads and some traces. This makes delidding unique as well, made easier with Der8auer’s Delide DieMate X (available in the US soon). This tutorial shows how to delid Intel Skylake X CPUs using the DieMate X, then how to apply liquid metal. We won't be covering re-sealing today.
Still, given the $1000-$2000 cost with these CPUs, an error is an expensive one. We’ve put together a tutorial on the delid and liquid metal application process.
Disclaimer: This is done entirely at your own risk. You assume all responsibility for any damage done to CPUs. We will do our best to detail this process so that you can safely follow our steps, and following carefully will minimize risk. Ultimately, the risk exists primarily in (1) applying too much force or failing to level the CPU, both easily solved, or (2) applying liquid metal in a way that shorts components.
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