The world has gone crazy for Nvidia -- or at least, Wall Street has. The stock has almost single-handedly lifted the entire market due to its monster valuation and latest, monster quarter. But the largest companies in the world are also typically the most well-known… and Nvidia is far from being a household name. And the last time a tech company without mass brand recognition became the most valuable in the world? That was Cisco in the late 90s. Is another bubble brewing? This week on TechCheck, the stock everyone owns and no one knows.