New version OCCT stability test
I thought this deserves to be in news. One of the best quick stability tests is OCCT. New version 2.0 with built-in monitoring and improved error detection.
From my experience if you pass custom test 1-2hours then you will be 99.9% stable on every other normal application such as gaming, encoding etc.
If you have error in this, prime will fail after as long as 10+ hours, so it detects error much sooner :)
http://www.ocbase.com/perestroika_en/
Direct download link:
http://www.ocbase.com/download.php?fileext=zip