Always a BSOD?
BSOD = something else
Black screen = PSU
Morphological is quite good (efficiency wise) but it makes text look hideous.
Supersample is best quality as it refines textures too.
Got a Xonar DX, it's good enough but not that much better than the onboard on my Crosshair IV, you're really just paying for the EAX software....
Might want to invest in the new 448 core 560Ti's