The raspberry pi 4 has one of the fastest CPU on a SBC , but it doesn’t come with any cooler ,
The raspberry is indeed capable of running without a cooler , but if you do anything other than idling, or something very lightweight like pihole, you are going to thermal throttle.

Since i have a old intel cpu cooler laying around i figured i could adapt it to cool my raspberry pi.

the cooler is way to big to be used the way it was designed. so i need to cut the cooler with a metal saw to make a new flat face , and put part of the cooler on the raspberry pi CPU.

after cutting the cooler you can see that i was far from having a flat surface to put in contact with the cpu.

To flatten the surface , I used a sanding disc fixed on my drill

After sanding the bumps , I obtained a kind of flat surface ,
i’m aware that it’s not truly flat , so to remedy that fact , i putted some thermal paste on the cpu surface.
The thermal compound will fill any irregularities enabling a good contact between the cpu and cooler.

Then to maintain the cooler flat on the cpu surface , i added a rubber band around the raspberry .
It will help put pressure on the radiator keeping it well pressed on the raspberry cpu