Hardware system information

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.

While Speccy looks nice, it seems to lack any real sort of monitoring. You can see the temperature of things like your CPU, GPU, and other hardware, but that's about it. You can't use it to watch things like CPU, GPU, or RAM usage, which, in my opinion, are much needed bits of information for any useful hardware monitoring tool these days. Programs like HWiNFO (free) or AIDA64 (paid), will give you much more information about your system, overall. Hardware Monitor is another choice which is free, but it lacks either GPU usage or GPU VRAM when it comes to monitoring (I think it's GPU VRAM usage). I'm sure there are others, as well, but those are all I've used.

Also, HWiNFO and MSI Afterburner will tie into the RivaTuner Statistics Server program which will then allow you to overlay that information onto your games.

I use Speccy on my work laptop just to monitor temperatures and its pretty light weight. But MSI afterburner + RivaTuner is on my home machine, I use it to control my gpu overclock and fan curve and monitor cpu and gpu data points and overclock GPU RAM.