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.
Our 7900X delidding benchmarks weren’t published by coincidence: Today, we’re expanding on our liquid metal vs. Intel TIM testing with the new Intel i9-7960X and i9-7980XE CPUs, the 16C and 18C Skylake-X parts, respectively. These CPUs are Intel’s highest multithreaded performers in this segment, and are priced alongside that status – the 7960X costs $1700, with the 7980XE at $2000.
Rather than focusing entirely on delidding and thermal benchmarks, we’ll also be including power testing and some production benchmarks (Blender, Premiere). This review of the Intel i9-7960X and i9-7980XE will primarily test thermals, power, delidded thermals, liquid metal thermals, rendering benchmarks, and some synthetics.
Recapping the previous test approach for delidding & liquid metal:
There are many reasons that Intel may have opted for TIM with their CPUs, and given that the company hasn’t offered a statement of substance, we really have no exact idea of why different materials are selected. Using TIM could be a matter of cost – as seems to be the default assumption – and spend, it could be an undisclosed engineering challenge to do with yields (with solder), it could be for government or legal grants pertaining to environmental conscientiousness, or related to conflict-free advertisements, or any number of other things. We don’t know. What we do know, and what we can test, is the efficacy of the TIM as opposed to alternatives. Intel’s statement pertaining to usage of TIM on HEDT (or any) CPUs effectively paraphrases as “as this relates to manufacturing process, we do not discuss it.” Intel sees this as a proprietary process, and so the subject matter is sensitive to share.
With an i7-7700K, TIM is perhaps more defensible – it’s certainly cheaper, and that’s a cheaper part. Once we start looking at the 7900X and other CPUs of a similar class, the ability to argue in favor of Dow Corning’s TIM weakens. To the credit of both Intel and Dow Corning, the TIM selected is highly durable to thermal cycling – it’ll last a long time, won’t need replacement, and shouldn’t exhibit any serious cracking or aging issues in any meaningful amount of time. The usable life of the platform will expire prior to the CPU’s operability, in essence.
But that doesn’t mean there aren’t better solutions. Intel has used solder before – there’s precedent for it – and certainly there exist thermal solutions with greater transfer capabilities than what’s used on most of Intel’s CPUs.
Today's video showed some of the process of delidding the i9-7900X -- again, following our Computex delid -- and learning how to use liquid metal. It's a first step, and one that we can learn from. The process has already been applied toward dozens of benchmarks, the charts for which are in the creation stage right now. We'll be working on the 7900X thermal and power content over the weekend, leading to a much greater content piece thereafter. It'll all be focused on thermals and power.
As for the 7900X, the delid was fairly straight forward: We used Der8auer's same Delid DieMate tool that we used at Computex, but now with updated hardware. A few notes on this: After the first delid, we learned that the "clamp" (pressing vertically) is meant to reseal and hold the IHS + substrate still. It is not needed for the actual delid process, so that's one of the newly learned aspects of this. The biggest point of education was the liquid metal application process, as LM gets everywhere and spreads sufficiently without anything close to the size of 'blob' you'd use for TIM.
Der8auer just delidded his high core-count Skylake-X CPU (12C to 18C), using the same kit that we used in our i9-7900X delidding video from Computex. Der8auer’s findings reveal a larger die than the 10C 7900X that we previously delidded, though the 12-18C units are ultimately using a die with disabled cores from the higher-end Xeon line. The delid also teaches us, critically, that even the 7920X CPUs are still not soldered. This isn’t necessarily a surprise, seeing as Intel’s operation has avoided soldering for the other recent CPUs, but we’re hoping that future Intel product lines move back to solder. Der8auer hasn't posted his findings of the 18C parts yet, so there is still room for a change -- but solder is looking unlikely.
Following our recent delidding of the Intel i9-7900X, we received a few questions asking for the die size and CPU size of the new 10C/20T Intel CPU. We decided to return to the GSkill booth, where overclocker Der8auer helped us delid the CPU, to take some measurements. The original delidding video is here.
On to the sizes: This was measured with a media gift ruler on a show floor, so it’s accurate enough. Millimeters are millimeters.
We ran into professional overclocker Der8auer at G.Skill’s Computex booth, who was keen to give us a hands-on delidding demonstration of a new 10C/20T Intel Skylake-X CPU. During the process, we also got our first real hands-on look at the CPU substrate and package – interesting in its own right – and underlying thermal compound choice. The lack of solder could have an explanation in chip longevity, something we’ll talk about a bit later.
This process involves Der8auer’s new delidding kit, an Allen wrench (looked like a 5mm wrench), and some force. Nothing difficult. The process is identical for both KBL-X and SKY-X, with the disclaimer that larger SKY-X CPU dies (like 14-18C chips) could pose some difficulties with extra capacitor density surrounding the CPU die. There’s much greater risk of damaging or destroying the 14C to 18C CPUs given this challenge, and although the 10C CPU was trivial, risk of damage is also present. SMD components sit close to the outer glue of the IHS, which means that delidding could potentially rip one of the SMDs off of the substrate. The SMDs on the sides of the CPU die are for memory channels, with the capacitor and RFID chip in the corner being less critical.
At the tail-end of a one-day trip across the country, this episode of Ask GN tides us over until our weekend burst of further content production. We’re currently working on turning around a few case reviews, some game benchmarks, and implementing new thermal calibrators and high-end equipment.
In the meantime, this episode addresses questions involving “doubled” DRAM prices, delidding plans for the i7-7700K, contact between a heatsink and the back of a video card, and a few other topics. Check back posthaste as we’ll ramp into publication of our i5-7600K review within the next day.
Video below, timestamps below that:
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