Everyone has their own opinion on stress testing. However, let's be sure about one thing: the more stress testing it can handle, the more stable it is. Or in other words: the more peace of mind you have about its stability.
Some excellent programs to use are:
Of course, this needs to combined with real-world use as well.
Now, regarding Furmark, switch from "Benchmarking" to "Stability Test" so that it can run infinitely. Also, use "Displacement mapping" as well. For the resolution, you can try different ones, but of course you can also just stick it in full screen at your native resolution. The "MSAA Samples" is Multisamping Antialiasing. More is not always more stressful (more is not always better), so don't be afraid to leave it at None, or to use 2x or 4x.
Regarding EVGA OC Scanner: use the settings in the screenshot I linked above, and let it go for 2 full hours. It actually won't run any longer than that.
Regarding OCCT, the same rules for Furmark's MSAA apply for OCCT's Shader Complexity: more is not always better. Oh, and OCCT's test doesn't have a fun animation to watch. It's just a stationary image. The same thing is true for EVGA's OC Scanner: when using the settings I recommend (which were recommended to me by our resident experts here on OCN), it doesn't animate the iimage. It's kinda the same principle as ATiTool: when just watching ATiTool's "3D View", the furry cube animates. But when scanning for artifacts, it doesn't.
I think i like FurMark.. that thing is a beast! (pun intended).
FYI - Furmark is like the big ugly bully cousin of Kombuster. LOL
Thanks for the info!! +1