I have tried all kinds of gaming benchmarks and onboard performance tests, and still the best one I have found is from a game nearly three years old…Crysis. No other game pushes all three relevant systems: CPU, memory, and VGA, to the extent that Crysis does. It will find instability in a system where no other benchmark does, especially with the CPU and memory. Settings were: High, CPU Test, 2xAA, 1280 x 900
Another older DX10 benchmark I like is Call of Juarez. It doesn't push the memory hard like Crysis, but does require a powerful CPU and good graphics card to get any kind of FPS. Of course this system is powerful enough to get awesome frame rates. Settings were: High, 2xAA, 1280 x 900