Sound is an integral part of the overall computer experience these days. It has been years ever since people have been able get sounds emanating from computers. Computers used to require soundcards, but apparently it seems like they have been replaced by onboard solutions in contemporary motherboards?
Personally, I think not. Yes, there are different grades of onboard audio solutions from the two main onboard competitors, Realtek Semiconductor and VIA Technologies. They range from really basic to what they claim as HTPC class. However, even with the HTPC class onboard chips like the ever popular ALC889/1200, they still cannot fully compete against the most simple sound card like the ASUS Xonar DS or the Auzentech X-Raider 7.1. Even the “next-generation” onboard solutions like the ALC892 and the VT1828S can't compete with the card options. They may be good for basic listening, but if you have even a cheap $70 speaker system, you would still be missing out on its full potential by sticking to onboard.
Now, you might be asking why, why on Earth should I spend at least $50 on a soundcard when my onboard sounds just fine? It all boils down to something called a Signal-to-Noise ratio (SNR). SNR is usually measured in decibels, the higher the ratio, the better the sound. Electronics, especially sound reproduction systems like soundchips and soundcards are susceptible to noise caused by electrical interference. The higher the SNR, the crisper your audio will become since it won't sound muddled due to the interference. However, SNR alone doesn't decide how crisp your sound will be outputted. Other things to consider is the chipset, Operational Amplifiers (OPAMPs), Analog-to-Digital Converter (ADC) and Digital-to-Analog Converter (DAC).
Normally, onboard solutions are an all-in-one solution where the ADC and DAC are both integrated into a single chip. The ADC and DAC usually found inside the onboard audio chips also are considered low grade due to manufacturers want to provide a low-cost solution. Additionally, onboard solutions tend to use utilize CPU cycles in order to produce sound whereas soundchips may be able to offload these sound processing. Some chips are even able to fully hardware accelerate every aspect of signal reproduction including 3D sound.
Although modern sound cards are no longer a necessity as they once were, anyone who spends a bulk of their music listening experience on the computers should do themselves a favour and get themselves a soundcard. Something like the ASUS Xonar D1, Auzentech X-Plosion, Creative SoundBlaster X-Fi Titanium or the HT Omega Striker 7.1 are excellent solutions for the gamer and the HTPC builder.