I am upgrading my pc soon and would prefer to have decent sound but, as I do not have a big enough budget, I have to rely on the onboard sound of the new motherboard.

The most common audio codecs used, are the Realtek ALC650/655/658. I have read up on the codecs' features on the website http://www.realtek.com.tw/products/products1-1.aspx?lineid=5 and, in theory, it looks acceptable.

I would, however, appreciate any views from first-hand experience concerning the quality and performance of the codecs, esp. the ALC655 (it is the most common of the 3). The 3D sound features (EAX, A3D, HRTF, Sensaura 3DPA, etc.) are of special concern.

Thanks

Well, you're not going to get the same quality as if you had a pci sound card, and in my experience i've gotten noise (machine noise, etc) in the sound stream if i listen to onboard audio with headphones or other sensitive speakers. However, if you absolutely cannot afford to buy even a value sound card (maybe something used off of ebay?), then this seems to be your best option, and I wouldn't worry about the sound so much as the quality of the motherboard it's on.