From what I understand, even Cosmic Rays can affect the life of silicon chips. But what we all want to know is, exactly how many years will silicon chips last on average? And will that exceed a human life span? It would appear one of you with library access would need to consult this book for the possible answer to that very question:

http://resources.metapress.com/pdf-preview.axd?code=v166l810q7527310&size=largest