[ohazi]

This kind of CPU upgrade was all but supported by the manufacturer.

Unlike modern laptops, the T430 motherboard had a socketed CPU (like a desktop motherboard). Upgrading the CPU was only marginally more difficult than upgrading the RAM (as long as the replacement CPU had the same package/pinout and was supported by the chipset). Lenovo datasheets would even give you a table of every CPU configuration they tested.

The "hardcore guys" mentioned by the parent are installing bodged motherboards that were never designed to fit in a given model's enclosure, occasionally doing major board surgery to make it work.