2 things:
1. Your ram is probably not 1.5v ram since there are very few ram sets that run at 1.5v over 1866mhz (most seem to be 1.65v, which is not recommended for the Haswell Cpus). Double check to make sure that your ram is 1.5v
2. The corsair CX series is corsair's budget psu and has some lower quality components (chinese capacitors), you should try to find something from XFX, Seasonic, or the Corsair AX/HX/TX series (no RM/CX/CS/VS series)
Edit: About the sound card, you will not need one for normal usage, the motherboards sound is actually really good and you would probably need a 50-100+ sound card to beat its quality in a significant way. Now, if you need some particular sound related sockets for sound recording or something then that would be a different story.