I really miss the customization that older laptops offered, especially the socketed CPUs. I remember putting a i7-3840QM in my T430 and having it shut down due to overheating every few minutes to the point where I had to install the heat sink from the GPU model. Was fun tinkering around with it and I wish modern laptops had a similar level of hackability.
Hah I'm doing this with some models of that same era judging by the CPU you cited. I had frankensteined one laptop from like the best parts out of three I had from that era, got xubuntu on it, running fine-ish but the Wi-Fi antenna ran through the on-board display chassis, which was destroyed. Took off the top clamshell, was gonna put ether in it and use as a desktop, but oops! The clip holding ethernet cable fell out during disassembly! No prob, pop it back open, oops! One of the screws holding the mobo is stripped! (Also, wife goes into labor while everything disassembled) No sweat, get something from ace to extract. I think I ended up throwing it back together and not testing?
Forgot about it for a couple years, wanted to put opnsense on it and see if I could replace stock equipment leased from ISP, nope. No display.
Fun to a point but probably should just spring for a used thinclient at this point, but prices are scary and I hate letting all this hw go to waste
Never managed to get one myself, but Framework laptops could be your thing as well?