I dreamed of owning an Apple computer back in the 1980's....but could never afford one. I settled for an Atari ST and was very happy with it for a number of years (long past when I should have moved on) but still couldn't afford a Mac of any sort. Until, way back in the early 2000's I started reading about how G3 iBook's video chips were delaminating off the logic boards due to heat affecting the solder. (It was done using a ball grid array).
There was supposedly a fix using a lighted tea candle placed on the chip and leaving it to melt the solder back on, all without totally destroying the contacts by overheating/pressuring them. I bought my first non-working iBook online and began trying this out for myself! (with VERY mixed results).
From there, I began to hunt down old Apple laptops that I could "fix" and resell. Eventually I moved on to G4 and Macbook Pro laptops and got rather good at taking them apart, sorting out what was wrong with them and fixing them. Then I bought my first (fully working) G5 tower and I was off! I owned a Mac that would have cost thousands back when it was new....for only a few hundred dollars.
Laptops have come and gone now. I stopped buying them up at around the 2013 mark, when they got steadily harder to take apart. Macbook Airs were my specialty. Swollen batteries were removed and replaced, whole logic boards taken out and transplanted, RAM was tested and swapped. About a year ago I sold off ALL my remaining Mac Laptop parts (for much less than I would have got if I had done it 6 months before) and all I work on now is 2009 - 2012 Mac Pro towers. It's been a great journey and I learned a lot. On this page, if time allows, I will include links to sites where you can learn about keeping older Macs alive and up to date, as well as some shots of my current Mac Pro setup.
As promised, here are some links to updating your Mac's OSX to (closer to) the latest version...even if your hardware does NOT support it. In other words, you can keep machines like the 2008 - 2012 Mac Pro as a viable alternative to a (much more expensive) new system. This is done using OPENCORE.
Here is a link to an introduction to Opencore: https://dortania.github.io/OpenCore-Legacy-Patcher/
This is a link to older Mac machines that can be used with Opencore: https://dortania.github.io/OpenCore-Legacy-Patcher/MODELS.html
My own computer is a 2009 Mac Pro with two 6 core Xeons and 96Gb RAM (DDR3)