I've got a mobo that has two SATA ports, and the headers for two more. Would it be possible to solder in two more ports? I've checked the southbridge, and it supports four. I'm not sure whether the bios supports four though. And before you ask, yes I know about expansion cards for twenty bucks. I'd just like to know if it's possible, and if so, any idea where I could buy the connectors?
I don't know of anyone with soldering skills that good, so I've never seen it been done before. If you think you can solder them in (and the traces are still in the board) then go for it. Find someone with any dead board on your local CL?
My soldering skills and, just as importantly the equipment I have available, are that good (40 years of professional experience and 10 more as a hobbyist).
But regardless of skill level, doing what you want to a working motherboard just isn't worth the risk of ruining the board even if it is a cheapy G41 motherboard. Leaving the soldering tip on the board a couple of seconds too long while you are cleaning out the holes will delaminate some of those really small PCB traces.