Especially when we consider AMD and Intel, we tend to use those names even after the final product is announced (and the codename is retired) to differentiate different processors in an increasingly confusing lineup of CPUs. '
A recent blog post over at Intel sheds some light on the code-naming process - the ways how names are selected from a limited list of options and the legal as well as in-house challenges. Both AMD and Intel usually go after public places that cannot be trademarked and do not carry any risk of lawsuits. Until recently, AMD used the locations of Formula 1 race tracks (a choice made due the company's involvement with Ferrari) and Intel has been using geographical places "that can be located on a map", thanks to Frank Zappa.
According to Intel, the company used "fun" and artist-related code-names before such as the "Joplin" or "Morrsion", but was legally challenged when the Frank Zappa Estate was not too happy when it heard about "Intel Zappa". Intel previously also used Disney names, planets and cartoon characters. "There’ve been all sorts of names,” Intel's Russ Hampsten said. “We used planets, moons, cartoon characters - we even had a dinosaur series of codenames around the time ‘Jurassic Park’ came out. My all-time favorite was probably ‘The Raptor.’ It was interesting, fun and it sounded mean.”
Sandy Bridge is a rather boring example. The chip was originally named "Gesher", which means "bridge" in Hebrew. However, Intel discarded the name when it was discussed that Gesher is also the name of a former unsuccessful political party in Israel. While Sandy Bridge sounds like a place on a map, it isn't: "Despite sharing its name with a bridge in Singapore and a historic town in West Tennessee, Sandy Bridge isn’t named for an actual place," Intel said. "Instead, it’s a result of a switch, and a suggestion from upper management following a meeting with analysts."
The successor of the current Sandy Bridge generation was originally supposed to be called, Molalla, after a town in Oregon. However, that name isn't especially easy to pronounce in all languages, so the company looked for a different name. Eventually, Haswell was chosen. Haswell is "a town claiming the country’s smallest jail, Intel said.""I had to go all the way to Eastern Colorado and a town of under 100 in population to get a tolerable name not taken or trademarked,” Russ Hampsten said.