Intel do both. Depends on the plant upgradeability and local infrastructure. Fab 42 is a ground up new build and was planned a few years back. Being able to validate/QA </=14nm without disrupting their older processes. Fab 42 shares the site at Chandler, Arizona with Fab 12 (which makes chipsets on 65nm) and Fab 32 ( which makes CPU on 45 and 32nm). ( Fab's 12 and 32 are due to be upgraded in the near future- presumeably once Fab 42 is up to capacity)Does Intel have to build a new factory everytime they go down to a smaller process? Do they continue to use their old fabs? Or later turn them into smaller process fabs? I see a lot of articles about them building fabs, this seems very expensive.