100C is the TJMax but you will lose stability at 80C for the Intel Core 2 Quad Q6600. It could be anything from case airflow (common), to using a stock heatsink and fan. Typically modders/system builders will want to replace the stock Intel heatsink and fan with Arctic Silver thermal compound and a professional heatsink/fan. This is not necessarily required however, as you are around 46.1C on idle. Try to determine your temp at max load using prime95 and see if you go near 70C or 80. If you do, you need to start looking at it as a serious problem.