This is an unusual modding to say the least. We always expect aesthetic and technical feats when we talk about modding. This is clearly not the case here since the author ‘s concern was to reduce the noise generated by the fan that comes with the box version of the i5-12400, which can be particularly noisy when the CPU is heavily used. First of all, the observation starts from the difference between the heatsink of the 12th generation i5 and the one of the bigger models. 
The heatsink on the right has an extra height and a “sleeve” which has not only an aesthetic purpose since it allows to channel the air flow. With this in mind, and equipped only with paper and tape, our DIY friend created a cap from a piece of paper, gluing the ends together to form a cylinder. With a bit of skill he was able to fit the paper inside without the fan touching it during operation.
This weekend: cheap DIY 😉
If the approach starts to make you smile, you will understand that the game is worth the candle. Because by multiplying the tests by varying the height of the sleeve, the impact, especially on the noise, was more than significant. The author discovered that a 1-inch sleeve greatly reduced noise. The cooler was 8 dB quieter than the original cooler, which is clearly noticeable. Unfortunately, this resulted in an increase in the maximum temperature of the processor, which went up to 85 ° C. After a few more paper cuts, with sleeves up to 3 inches high, he opted for the optimal sleeve of 1.7 inches (about 4.3cm). The CPU in this configuration was able to maintain the same max temperature under load as with the original fridge, while reducing noise levels by 6 dB. If you want to try this modification, remember that it’s free (the ventirad being delivered with it), easy and almost risk-free… The weekend is going to be rainy…