Depends on what you want to stress. If you are just looking for maximum temps, I'd suggest Prime95 version 26.6, use the small fft. This gives a good, solid 100% cpu load, unlike other tests, so gives a pretty accurate temp accounting. If you want to stability test, I'd use Asus RealBench, which doesn't do much for temps, but does a lot of mixing/matching using the ram, cpu, gpu etc so really puts the pc through a workout. For gpu stress, I like MSI kombuster, there's several different ways there to punish any particular part of the gpu, some like Furmark which is more like to RealBench, and punishes the gpu in a bunch of ways simultaneously.