Ok, you can use Supreme Commander to check stability of the whole setup, but if your PC will crash how you can check what has failed You need to stress test all your compontents separately first then you can use Supreme Commander. I'm using the following to test stability:

For CPU:

OCCT, Orthos, Prime, SuperPi

Running OCCT for hour if the results are fine then Orhos 8h, then you can run prime and superpi. Wprime is very good also

For Memory:

Memtest+ and Goldmemory. Goldmem is in my opinion the best memory software tester It can detect errors when in Memtest+ everything was fine.

I'm running memtest+ and goldmem for 8-14 hours.

One good thing with memtest+ is the information it provides. It is not stated in manual but I've collected in my mind years of other people experience with that software

Please look at that post for example:

http://www.bleedinedge.com/forum/showthread.php?t=442

Then if all above tests are fine run once the following sequence (it's even more useful if you have overclocked you graphics card):

3dmark 2001, then 3dmark 2003, 2005 and 2006. 3dmark 2001 is very sensitive to overclock If you are successful then loop 3dmark 2006 for few hours

If above test were ok you can play Supreme Commander with a pleasure