From Alex van Kaam:
Motherboard Monitor (MBM) is a tool that will display information from the sensor chips on your motherboard in your Windows system tray. MBM supports a wide range of chipsets and sensor chip combinations. It can sense temps from CPU, HDD, and GFX. It does also sense fan speeds. If it senses that your hardware is overheated it can protect it by shutting it down (user configured). To see if MBM5 supports your hardware check out the Motherboard List. It does also record all temps and fans for later viewing. This is a great invention if you want to overclock. Example to see how well cooled your computer runs over a time. Full load or idle time. Its recomended for all home built systems. Specially if you make your own heat sinks or just test you newly overclocked CPU or GFX card.