What is the difference between 5.1, 6, 7.1, and 8 channel sound cards in a motherboard?

NerdyComputerGuy

Distinguished
The difference isn't noticable unless you are running a surrond sound set, ussully we compare 5.1 surround sound to 7.1 surround sound, If you do not have any 7.1 surround sound compliant devices then 7.1 is useless, 5.1 is the most common on all motherboards today and is the the perfect choice

My recommendation:
5.1

Comparison Chart
5.1 Surround Sound vs 7.1 Surround Sound
http://www.diffen.com/difference/5.1_Surround_Sound_vs_7.1_Surround_Sound