MS SQL Page split confusion

I am a bit confused about page splits in MS SQL and I'm looking for a definitive answer. There seem to be two versions of the story: 1 - Fillfactor only affects how full pages are at the time the index is created/rebuilt. Page splits are always 50/50 2 - Fillfactor also affects how pages are split. So if there is 70% fillfactor and a page overflows, it will split 70/30 Thanks a lot