I will also not be using speakers, just the gaming headset which is 7.1!
Do i need a sound card for this setup/headset? I still want really clear sound and to be able to tell where my opponents are in games like BF3 and MW3! Will i get optimal sound that wond be to noticable with this headset and motherboard?
I think it really comes down to your "ear",as most people don't hear a big difference and what kind of gaming you do most of the time. FPS will benefit from a separate card, though it won't give you an "edge" regarding sound placement (as in I heard him come up behind me) as much as it will just be more immersive. The surround will be a bit better with a real sound card and your lows (bass like explosions) and highs (more prominent on music than movies or gaming) will seem fuller. I switched to a x-fi from on board for music mostly and I can't say I hear a big difference on something like star craft 2 but when I am watching movies and listening to music there is a definitely an improvement.
If music isn't that important, then it depends on your budget and your rig. I think your typical gamer would benefit from sinking that money into more ram or a better GPU if budget is an issue.
sorry for the poor train fo thought, still need coffee
To reiterate, you don't need an additional sound card. If you want one, it will improve overall performance (if you get tge right card), but in the OP's case, it isn't necessary at all. The OP will be using USB sound via a Logitech headset.