Okay, so I just want you to know that sound cards do nothing if not downgrading your system.
What a sound card does is it take the audio file coming in as binary and either decodes or amplifies it or both depending on the card. If this sound card is external then this may not be a problem but if it is internal do not get it. Noise from your system will interfere with the sound card and won't make much of a change.
It's been said that any given sound card does what your motherboard's sound card already does but the motherboard does it 5 times better, think about that.
So to answer your question, a sound card has no positive perks, if it's a high end build the motherboard likely has a better sound already.
For in-game sound, a lot of people say sound cards and curtain headphones give you surround sound but the truth is pretty much any computer with any pair of cans can simulate 5.1, 7.1 etc. Sound is not something you worry about taking your RAM and CPU power.
On other hand, having an external DAC (that's a Digital to Analog Converter) with an Amplifier will vastly improve your audio experience whether it be gaming or music, so I would go with that, but they are somewhat pricey.
In the end, you must remember that the audio industry is mostly held up by effective advertising, placebos, and other people believing in those ads and placebos. Never buy a sound card, or an internal sound card at the very least.
Good luck and have fun!