I wanted to upgrade my computer without having to change the CPU, the motherboard and the RAM (prices are currently high because of shortages). So I looked what CPU I could use with my 10-years-old motherboard in order to replace the 2500K.
And the answer was the 3770K that is similar to the 2500K but double the number of threads from to 4 to 8 (see Intel's comparison).
I found a 3770K at a decent price on eBay. But changing from the 2500K CPU to the 3770K was not an easy task. Here is how I did it.