Speccy is a system information tool that will give you detailed information on every component in your computer, as well as checking real-time temperatures.

http://www.piriform.com/speccy

Its commercial but it has a free version that still displays everything, just features such as support and auto-updates are disabled.

It is currently being recommended by Blizzard Support Forum Agent Dankorii in the Blizzard tech support forums. Would love to hear from people who have used other tools such as this.