USB 2.0 add-on card slower than onboard USB 2.0?

[CrazySaint]

I was looking at the EPoX 8K3A+ at newegg and saw the free USB 2.0 sound card and was wondering how much it would hurt USB 2.0 performance compared to the onboard USB 2.0 that many other boards have?

 

[Damascus]

Add-on cards are connected via the PCI bus, therefore they must compete with your
other PCI devices for bandwidth. Onboard ports usually have their own dedicated
bus.

 

[Erasmus-X]

Ummmm.........no.

The built-in USB controller on a typical motherboard is always attached to the PCI bus in some way. Therefore, it too will compete with the rest of the devices on the bus for bandwidth. The same thing goes for any other communications ports (serial, parallel, keyboard/mouse).

The performance of an add-on card will generally be similar to that of a built-in one. This of course will vary, as some USB chipsets are better than others.

 

[MoMeanMugs]

Damascus, if I told you my computer drives a bus, would you believe me?

 

[Damascus]

I thought that stuff built-into the chipset like ports, IDE, etc. aren't connected to the PCI bus...
hmm guess I was wrong.

 

[CrazySaint]

USB 2.0 isn't built into the VIA AMD chipsets (yet).

 

[BrunoPuntzJones]

Originally posted by: CrazySaint
USB 2.0 isn't built into the VIA AMD chipsets (yet).

You sure?

 

[CrazySaint]

Originally posted by: BrunoPuntzJones

Originally posted by: CrazySaint
USB 2.0 isn't built into the VIA AMD chipsets (yet).

You sure?

Yes, quite. No mention of USB 2.0 there. I checked the page you linked to, what does a MSI board that has USB 2.0 based on a VIA chipset have to do with VIA chipsets having USB 2.0 built in? AMD boards based on VIA chipsets that have USB 2.0 on them, get it via a seperate chip on the board.

 

[BrunoPuntzJones]

Bah stand corrected, I misunderstood your statement.

Thought you meant are there any AMD boards with 2.0 support. You meant any with native 2.0 support in the chipset.

 

[CrazySaint]

Ah, I get ya. Yeah, I was talking about native to the chipset, 'cuz apparantly current USB 2.0 solutions are "PCI on board" which is the same as having them on a PCI card in a slot.

 

[Lord Evermore]

Not all onchip controllers like USB or IDE are actually run through the PCI bus.

As WetWilly pointed out in this thread, some boards are now coming with a BIOS option (and some have it hidden) to link the onchip controllers to the PCI bus or to run them on their own dedicated bus to the southbridge. Onchip controllers are built into the southbridge, so there is no technical reason they need to be linked to the PCI bus in any way, and obviously performance can be increased if they're not fighting other devices for the PCI bandwidth (though they all have to share the north-southbridge bandwidth, which is more than sufficient).

 

[CrazySaint]

Lord Evermore, thanks for the link. Any idea if any boards based on the KT333 chipset have that option available?

 

[Lord Evermore]

I only just learned about it in that thread, so no, I have no idea. I would have assumed that the design of the southbridges now would mean the onchip controllers always used a dedicated bus. Not even sure exactly what that option does - whether it actually controls the onchip controller via the PCI bus, or if it just locks the frequency as if it was on the PCI bus.