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Improving the Thermal Performance of the Intel Kaby Lake CPU

Manufacturer: RockIt Cool

Introduction

Introduction

With the introduction of the Intel Kaby Lake processors and Intel Z270 chipset, unprecedented overclocking became the norm. The new processors easily hit a core speed of 5.0GHz with little more than CPU core voltage tweaking. This overclocking performance increase came with a price tag. The Kaby Lake processor runs significantly hotter than previous generation processors, a seeming reversal in temperature trends from previous generation Intel CPUs. At stock settings, the individual cores in the CPU were recording in testing at hitting up to 65C - and that's with a high performance water loop cooling the processor. Per reports from various enthusiasts sites, Intel used inferior TIM (thermal interface material) in between the CPU die and underside of the CPU heat spreader, leading to increased temperatures when compared with previous CPU generations (in particular Skylake). This temperature increase did not affect overclocking much since the CPU will hit 5.0GHz speed easily, but does impact the means necessary to hit those performance levels.

Like with the previous generation Haswell CPUs, a few of the more adventurous enthusiasts used known methods in an attempt to address the heat concerns of the Kaby Lake processor be delidding the processor. Unlike in the initial days of the Haswell processor, the delidding process is much more stream-lined with the availability of delidding kits from several vendors. The delidding process still involves physically removing the heat spreader from the CPU, and exposing the CPU die. However, instead of cooling the die directly, the "safer" approach is to clean the die and underside of the heat spreader, apply new TIM (thermal interface material), and re-affix the heat spreader to the CPU. Going this route instead of direct-die cooling is considered safer because no additional or exotic support mechanisms are needed to keep the CPU cooler from crushing your precious die. However, calling it safe is a bit of an over-statement, you are physically separating the heat spreader from the CPU surface and voiding your CPU warranty at the same time. Although if that was a concern, you probably wouldn't be reading this article in the first place.

Continue reading our Kaby Lake Relidding article!

However you choose to approach the process, the first step is separating the heat spreader from the processor PCB. The heat spreader is mounted to the PCB using an RTV-style adhesive ensuring a secure seal, protecting the fragile processor die from outside contaminants and influences. There are several ways to remove the heat spreader including using a manufactured delidding tool, the razor blade method, and the vise method. With all methods, you are attempting to separate the CPU PCB from the heat spreader without damaging the CPU die or components on the top or bottom sides of the CPU PCB.

Razor Blade Method

The razor blade method involves using a double-edged razor blade to cut through the RTV material fixing the heat spreader in place, gently prying the heat spreader from the CPU PCB's surface. You carefully work the blade very carefully under all four corners of the heat spreader to weaken the RTV bond and slowly pry the heat spreader up off of the CPU's surface. This method has many potential pitfalls though. One of the largest is the possibility of cutting into the CPU PCB surface while attempting to cut through the RTV holding the heat spreader in place. Another pitfall to avoid with this method is the possibility of cutting through the circuits along to the right and left of the CPU die. This is more likely to occur if you attempt to insert the blade too far underneath the heat spreader while attempting to cut through the RTV.

Vise Method

The vise method involves locking the CPU in place by the heat spreader in a bench vise and using a rubber mallet to forcibly remove the CPU PCB from the heat spreader. You basically place a wood block against the edge of the CPU PCB and lightly tap the wood block until you notice separation between the CPU PCB and the heat spreader. While this method seems much more prone to CPU destruction than the razor blade method, it is actually a much safer method and much less prone to pitfalls than the razor blade method. However, you do have to fix your processor's heat spreader in a vise. If you would like more details on this method, you can see our Haswell delidding article here.

Delidding Tool Method

While none of the methods can be considered 100% safe, using one of the commercially available delidding tools removes alot of the guess work and fudge factor inherent to the other methods. No matter which vendor's tool you choose to purchase, delidding the processor is as simple as placing the CPU into the device, locking it in place, and turning a screw which exerts sideways force to the heat spreader to pop it off. The mechanism securing the CPU ensures the the heat spreader does not travel too far once detached, minimizing the possibility of damage to the processor die or PCB top-mounted circuitry.

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Courtesy of RockIt Cool

View Full Size

Courtesy of RockIt Cool

For this endeavor, we chose to use the RockIt 88 delidding tool, purchased from RockIt Cool along with their LGA1150 re-lid kit because of their location in the US to cut down on shipping charges as well as the good reviews their product has gotten. In addition to the RockIt 88 tool, we used Coollaboratory Liquid Ultra thermal compound for the interface layer between the processor die and heat spreader, and black RTV adhesive to fix the heat spreader to the processor PCB surface.


March 13, 2017 | 02:19 PM - Posted by willmore

Yay, Morry's back!

March 13, 2017 | 03:03 PM - Posted by Zach Davis (not verified)

Great article guys!

March 13, 2017 | 03:48 PM - Posted by Mobile_Dom

I think the impressive thing is that not only did you receive a 20 degree delta on hottest temps, but how much easier it is to do with these kits now.

Though the fact the Ryzen IHS and TIM is already pretty great means you dont need to do this etc etc.

March 13, 2017 | 03:55 PM - Posted by Morry Teitelman

Very true there.  AMD took the solder route, similar to what Intel does with their LGA2011 processors.  Makes heat transfer and dissipation much more efficient.

March 13, 2017 | 04:27 PM - Posted by Jann5s

Intel TIM: Thermal Isolation Material, it works as advertised :D

joking aside....

I think it is a nearly a crime that intel can sell $300+ dollar cpus without proper TIM. It seems that the material they used is even worse than ketchup.

@Morry, do you have any tips for us about the expected lifetime of the Coollaboratory Liquid Metal? Is it advised to re-apply after a year? And would you then recommend using the adhesive to glue back the heat spreader?

March 13, 2017 | 04:56 PM - Posted by Morry Teitelman

Liquid metal application should last for the life of the proc.  This should be a "one and done" type procedure.  You could do it more then once, but every time you crack the heatspreader off the PCB, you risk ruining the proc.

As far as re-adhering the heatspreader to the proc PCB, I used black RTV.  relaively cheap, easily found as your local walmart or automotive store, and is electronics and plastic safe.

You *could* try naked cooling the CPU die, but I wouldn't recommend it, especially after my failed attempted with teh 4770K....

March 13, 2017 | 05:29 PM - Posted by Buyers

When HardOCP did their de-lid/re-lid testing on the 7700k/7600k processors, they attempted naked die cooling and it sounded really risky. Basically, the head spreader also spread the clamping force necessary to adequately seat the processor into the socket. Without the heat spreader, all that downward force is is isolated to the bare die unless you make some kind of shim. I think their results with bare die cooling was that it was only a few degrees better than just re-lidding with the better TIM, but not worth the added risk to the die.

March 14, 2017 | 01:20 PM - Posted by Anonymous (not verified)

"Intel TIM: Thermal Isolation Material, it works as advertised :D"

TIM is fine, it's the separation between the IHS and die surfaces that is the issue. If you delid and then relid and don't even touch the stock TIM, you'd get the same improvement in thermal performance.
https://forums.anandtech.com/threads/delidded-my-i7-3770k-loaded-tempera...

March 14, 2017 | 04:27 PM - Posted by Morry Teitelman

While that forum post from a few years back remains relavent to the conversation, it discussed delidding of an entirely different processor.  There may be an issue in the separation between IHS and die surface, but for the 7700 series, the TIM is most definately problematic.

Thanks...

March 13, 2017 | 06:33 PM - Posted by Admiral_Akbar

@Morry, it feels like you're missing an image near the bottom of page 1.

We go from "Next, carefully snap the Re-Lid hold down.." to "At this point, you are almost done. Before applying the black RTV.." without showing the application of the RTV

Hopefully I'm not imagining things

March 13, 2017 | 06:44 PM - Posted by Morry Teitelman

yeah, I noticed that too.  Unfortunately, I did not get a pic of the RTV applied to the heatspreader before putting humpty dumpty back together again. And I didn't want to press my luck after getting a good mating...

March 13, 2017 | 06:57 PM - Posted by Admiral_Akbar

True, a good mate is hard to find.

Maybe moving the picture with the headspeader down so it sits above "Screw the center screw into the torque plate and then carefully fix the torque plate in place over the..." would help?

March 13, 2017 | 09:02 PM - Posted by Morry Teitelman

Good idea, thanks for the input...

March 13, 2017 | 07:04 PM - Posted by John H (not verified)

Morry - Do you have any recommendations for a thermal paste that would last for years like the original TIM would? My only concern with de/re-lidding is you might need to reapply the paste in 2-3 years as it does dry out over time..

March 13, 2017 | 08:58 PM - Posted by Morry Teitelman

not entirely sure.  Some reports say that liquid ultra does degrade within a year, but on most of those forum posts, people were using direct die cooling without an IHS installed.  That introduces direct air contact as well as possible humidity affects.  The IHS would better protect the die area and the TIM from "open air" type affects...

March 13, 2017 | 10:35 PM - Posted by John H (not verified)

Good point. Thanks!

March 14, 2017 | 11:03 AM - Posted by Anonymous (not verified)

Morry, it looks like the original heatspreader adhesive application left a small air gap. The adhesive does not appear to make a closed loop all the way around the perimeter of the heatspreader. Did you replicate this when you re-adhered the HS to the PCB? If so, doesn't that allow air under the HS and potentially cause the open air/humidity issues?

March 14, 2017 | 11:20 AM - Posted by Morry Teitelman

I'm not sure if I left the gap when I resealed it.  While it is true that the gap would leave a section for air exchange, the IHS is very securely fixed to the PCB surface, so the gap is minimal.  So it still wouldn't be as greatly affected as a naked die would...

March 14, 2017 | 01:03 PM - Posted by Buyers

They leave an opening to let out air pressure created as the die heats up. Old processor IHS's used to have a small hole for this.

March 13, 2017 | 10:25 PM - Posted by Anonymous (not verified)

Sorry your onclusion is wrong. Conclusion should be that Intel is doing shit this time. How come an experienced CPU manufacturer like Intel does not make it better than all what they did in the past? Someone at Intel is paid way too much and should be fired. Teenagers still at school can do better.

March 15, 2017 | 12:25 PM - Posted by Dennis (not verified)

Scotch tape... for real?! You never heard of ESD i take it.
From now on use Anti Static Tape. Kapton Tape is my choice.

March 16, 2017 | 01:41 AM - Posted by Danny (not verified)

Nevertheless, delidding IHS voids warranty, and may possibly damage CPU unless he/she uses proper delidding tool.

March 16, 2017 | 03:36 PM - Posted by Anonymous (not verified)

Be careful with that Gallium. It eats aluminum and corrodes copper.

http://www.overclock.net/t/1313179/official-delidded-club-guide/14340#po...

March 19, 2017 | 02:15 PM - Posted by Anonymous (not verified)

Learn some stuff, guys:

http://overclocking.guide/the-truth-about-cpu-soldering/

When you consider the thermal density of these small dies, it is much easier to have micro-cracks in the solder due to constant thermal cycles, which will increase the chance of killing the CPU. That's the reason why Intel doesn't solder their mainstream chips ever since Ivy Bridge. They could get away with it with sandy because it was on a larger node.

While paste doesn't perform as well as solder, it eliminates this issue, which is why the Engineers went with it.

The reason why liquid metal wasn't used is because it was not necessary. As you can see in most reviews, you're only gaining a few degrees from your typical paste vs. liquid metal. Hardly meaningful from a temperature standpoint, and especially from a cost standpoint. Remember, Intel is making hundreds of thousands of these CPUs, and liquid metal isn't cheap, nor is it as easy to apply to a product as paste is.

The reason why we are seeing increased temperatures isn't primarily because of the TIM used, but because of the gap between the heatspreader and the die. The glue they use to stick the heatspreader to the die raises it away from the die. As you can see in PCPer's picture, they took all of that glue off, so of course heat transfer is going to be more efficient due to it being closer. But doing so greatly increases the risk of damaging the die, but so does delidding.

March 20, 2017 | 07:45 PM - Posted by Anonymous (not verified)

4.8GHz is very easy to get to with a decent cooler and airflow. So I'd be looking at a 300MHz increase if all goes well, or a 6.25% increase, for about $50.

On a CPU limited game at 50fps that's an extra 3.1fps. On a compiler run that's CPU limited it'll be 56.5 seconds instead of 60.

I love reading this stuff but I guess I'm old and jaded anymore, it's cool for bragging rights though ;) Thanks for the write-up and the pictures, I like that you kept it so concise and informative.

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