StressMyPC is a great portable freeware application with a simple premise: test how long your PC battery can go before the battery dies. You can start and stop the stress test for the CPU, perform a hardcore stress test of the CPU, stress the GPU and perform stress tests for the hard drive.
From Nenad Hrg:Let's see! How long can your laptop battery hold a charge? Or let your PC sweat like a .... Warning! Unstable and overclocked systems can be crashed.StressMyPC 2.66
is licensed as Freeware
for the Windows operating system / platform without restrictions. StressMyPC is available to all software users as a free download (Freeware).
StressMyPC Virus and Malware Tests:
For security reasons, you should also check out the StressMyPC virus and malware test
that has been uploaded; additional StressMyPC screenshots may be available, too.