Delidding a CPU is supposed to be the last word in CPU cooling. Removing the IHS and exposing the CPU die to either replace the TIM between the die and the IHS, or resort to direct-die cooling, is the ultimate way to bring down your CPU temperature. What needed a bench vice earlier is now possible with delid tools, but the risk of permanent damage to the CPU is still there. Besides, no one other than world record chasers needs to think about delidding their CPUs; the benefits aren't worth it to the average user.
It's not worth the hassle
What will you do with even lower temps?
Delidding used to be much more prevalent in enthusiast circles when the thermal interface material (TIM) between the IHS and the die used to be subpar. Removing the IHS to replace the TIM yielded massive thermal benefits, and nothing else came close. Today, however, the benefits of delidding aren't as attractive anymore. Over time, the TIM used by manufacturers under the IHS has improved, and going through the hassle of delidding your CPU is far less attractive.
All you need to cool your CPU is a high-end liquid cooler or a custom watercooling loop, and that's only if you aren't satisfied with the results from your air cooler. For the overwhelming majority of users (like myself), as long as the CPU remains below 80℃ during gaming or other workloads, there's no point in taking the CPU apart. It's still a fun project, and will certainly lead to reduced temps, but after a point, lower temps don't really do anything for the average user.
I have a Ryzen 7 5700X, a 65W TDP processor that isn't exactly a power-hungry chip. I don't see myself delidding a CPU ever, especially since I'm probably never buying anything other than a 6-core or an 8-core Ryzen X3D CPU in the future. Neither of those chips would need more than a decent liquid cooler or air cooler to keep them cool and happy.

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Integrated Lighting Yes
Fan Speed ~2,500 RPM
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Curiosity can kill the cat
Delidding remains a risky procedure

Source: Flickr
Delidding a CPU has become easier compared to the time when people needed a bench vice and even more complicated procedures to remove the IHS. With the delid tools from de8auer making the process simpler, the degree of risk might have come down, but it's still there. You can easily damage the CPU die if anything goes wrong. With one slip, you can damage the surface-mounted components situated right where the IHS is glued on.
Then there is the aspect of voiding your CPU warranty. Users who're looking for an easy fix to dramatically lower their CPU temps should think twice before popping the IHS. Even if you successfully delid your CPU and achieve lower-than-ever CPU temps, your CPU won't be covered if anything goes wrong later on, even if it's unrelated to the delidding process.
You should also know about the risks of handling liquid metal, which is usually the TIM of choice for "delidders." It's a conductive liquid, and can easily short the motherboard components around the socket if you spill it. You might just end up destroying more than just your CPU if you go down the delidding route.

This tool from Thermal Grizzly takes all the hard work out of delidding an AMD Ryzen 7000 series processor, so you can replace the factory solder job with liquid metal for better heat transfer.

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Delidding is best left to extreme overclockers
They need every Celsius drop they can get

Image: SkatterBencher (via YouTube)
There's CPU cooling, and then there's CPU cooling. Most people can stop at constructing their own custom loop, but some people want to go one step ahead and dabble in direct-die cooling. Short of using liquid nitrogen, direct-die cooling with liquid metal TIM is the best way to achieve record-breaking CPU temps. However, the only people who need to do this are extreme overclockers, YouTubers, and other enthusiasts who can accept the risks as well as some dead CPUs.
Cutting-edge CPU cooling needs CPU delidding — there's no way around it. However, everyone else who simply needs to tame their power-hungry CPU should not consider this risky procedure, especially since better solutions already exist. You can keep the most high-end chips cool with a custom loop or high-end liquid cooler, and enjoy the maximum performance that the chip can offer. Sure, you're technically "letting go" of extra performance by not delidding your CPU, but at that point, you're splitting hairs.

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Delidding a CPU should be, at best, your side project
CPU delidding is only relevant for extreme overclockers who're hunting for the next world record. For everyone else, the risk of permanent damage and loss of warranty means that they should only attempt this as a fun DIY project on an older CPU that they have no other use for. Maybe you'll successfully delid it and achieve crazy low temps, or maybe you'll kill the CPU forever. Even if it's the latter, you probably won't be that sad.

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