I'm thinking of building a motherboard
Guess what? I'm thinking of making a Palomino chip in my garage (if I had a garage 🙂 )
Anyway, if you're building your own mobo, will you also be making the chipset from scratch silicon? And the capacitors? Like the other said, it's virtually impossible unless you've had experience at MSI or something, but even then, buillding a 12-way mobo? Highly not possible.
You will need a green PCB (like 8 layer), lotsa traces and stuff, some capacitors, 12 socket 5's, some dimm slots for 1st generation SDRAM, some PCI slots, a chipset, the IDE plug thingy, etc. This is not something that even one who's worked at MSI would attempt. I don't recommend pursuing this course.