Nowadays, most mobos come with integrated 5.1 or 7.1 sound system, the audio jack allows you to hook up to at least 2.1 speaker system.
I remember back to earlier Intel Pentium time, sound card is a prerequisite when you buy a new computer because mobos do not have integrated audio chips.
So, today do we still need sound card?
Of course sound cards are still on sales, it could be better than integrated sound, but if you buy a very good speaker system, the on board audio chip will be able to deliver high definition sound for you.

what do u think?

Sorry, but that doesn't make sense. Even if you buy the best speaker system out there, it can play only in the quality that is delivered from the soundcard. So the answer should be: If you are audiophile and want the highest possible quality then buy a good speaker system and a good soundcard.

Answer: Yes you do need. If you want quality you need good sound card, good speaker set, good player, good source files.
Because they are cheap(not in money area but in construction) and cheap doesn't cut it when it comes to quality.

A very good sound card plus speaker system, won't be better than high end AV Receiver (e.g. Onkyo), right?

???
This is not related at all. Even a high-end AV receiver can only play what he gets delivered, and if you put crappy speakers on the receiver it nonetheless can't deliver good sound.

By the way, even Onkyo produces, besides their high end stuff, products for the consumer market (low and mid-end).

I think it's what you use your computer for.
Work,Office-the reg. 2 spk. set NO
Internet reading E-Mail, Facebook NO
Netflix--------Yes(maybe)
Games----------Yes(on Windows)
For Most Computer users the Onboard is just fine,Same for Video (? Blu-Ray HD )

Personally, I agree with you in the first person. I don't need a soundcard. I like quiet, and can put up with crap sound.

For others, (Like my son in the next room) a sound card is a necessity. There is also a huge difference in onboard sound card quality: Some onboard cards have ac'97 variants, which suck. Others have hda_intel variants, which are better. Audiophiles want hf sampling (192khz instead of 44khz), xlr inputs, low hd, tid (distortions) and kit that talks to audiophile mixers and effects.

The answer to this question is simple.

1) Plug in your speakers to the onboard sound jack.
2) Are you happy?

If yes, leave it alone, if no, buy a card.

1 members found this post helpful.

For example,
An Asus mobo has:
Onboard Audio

Audio Chipset Realtek ALC892
Audio Channels 8 Channels

Compare with:
Creative Sound Blaster X-Fi Titanium
Audio Chipset X-Fi
Channels 7.1
Sample Rate 96KHz
Digital Audio 24-bit

The ALC892 can't deliver 96kHz 24-bit sound?

If your interest in music is anything more than just playing some tunes quietly in the background, then the answer is yes, you do need a proper sound card. I used to record my guitar and could see the difference between the onboard audio card and a PCI Audiophile 2496. It isn't an expensive card but also has a MIDI I/O, which I used for my keyboard.

Comparing HDMI and optical fibre, they are both digital, which can deliver the best signal to speakers?

No digital signal is delivered to the speaker. In that case you need a separate D/A-converter and an amplifier. The quality of the resulting sound is almost solely dependent on those components.

I don't study Electronics Engineering, I do not know the details.
Of course, the speakers produce analog sound, it is the CD player send digital signal to AV Receiver or amplifier thru fibre optics cable or HDMI cable.

The 5.1 or 2.1 computer speaker systems have a central sub-woofer, it states that it has pre-amp, will that help in sound quality?