Is your PC behaving oddly? Maybe there's a hardware cause, a temperature or voltage problem. To find out you need a hardware monitor, and the first place to go looking is your motherboard manufacturer.
Asus PC Probe II, for instance, displays live information on motherboard voltages, temperatures and fan speeds. Play games or otherwise stress your hardware, watch the figures change, and you just might discover the real cause behind your PCs crashes, hangs and other issues.
If you'd like to give it a try then visit the Asus support site, search for your motherboard and check the available downloads.
http://support.asus.com/
Most motherboard manufacturers have their own equivalent tools, though, and many go much further. MSI Dual Core Center lets you overclock your system from Windows, for instance.
http://www.msi.com/index.php?func=downloadfile&dno=4902&type=utility
And Gigabyte EasyTune 6 provides easy access to many BIOS options from the desktop.
http://www.gigabyte.com.tw/Support/Motherboard/Utility_DownloadFile.aspx?FileType=Utility&FileID=86
Check your motherboard manufacturer's support site to see what downloads are available - you might be surprised just how powerful they can be.
