Hardware Monitoring Software

I recently built a unit and now have an very slight intermittent issue with the computer rebooting on it's own. I'm leaning towards the power supply due in fact I can hear a clicking noise when the unit recycles and the case I purchased came with no internal fan and when I purchased one and installed it, the unit rebooted constantly until I removed the fan. I'm thinking an inferior power supply. I'm interested in downloading a piece of software that is capable of monitoring system temperatures. Any sugguestions?

 

Back in the days when I was more concerned about temps I used Motherboard Monitor. I hear people mention Speedfan as well.

I don't use apps like these anymore because running an Athlon 64 in a well-ventilated full tower case my temps are very, very low.