Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
In article <df5535$fdo$04$1@news.t-online.com>, Stephan Grossklass
<sgrokla-nospam04q2@yahoo.de> wrote:
> Daniel Mandic schrieb:
>
> > Stephan Grossklass wrote:
> >
> >> Want Gb via CSA? Then you'd need the P4C800-E Deluxe. Otherwise some
> >> P4P800 variant in a current revision would also do. You should read up
> >> on this USB latchup issue though.
> [snip]
> >
> > P4C800-E Deluxe sounds well.
> >
> > What is GB via CSA?
>
> Gigabit Ethernet attached via CSA. This way it does not have to share
> the bandwidth with all the stuff on the lame PCI32/33 bus (which is not
> even sufficient for half-duplex GbE). Somewhat VL-bus-like.
>
http://www.intel.com/design/network/products/lan/controllers/82547ei.htm
>
> > I don´t think that more than one USB-HUB will be activated. Will there
> > be any troubles? Maybe two...
>
> You should really read what Paul wrote here on the subject. Google
> Groups exists. It's certainly explained somewhere on the web as well.
>
> Stephan
There is a latchup problem on the ICH5 Southbridge. The main
trigger condition seems to be, if a bit of static discharge
enters a USB port. This causes a conduction path to form
between VCC and GND, and a lot of current flows. (The only way
to stop the current flow, is to flip the switch on the back
of the computer. And you cannot do that fast enough, before
the damage is done.) The Southbridge gets hot enough, that a
burn mark forms at a certain point on the top of the chip.
The motherboard won't boot any more, for most of these failures.
In some cases, only the power to the USB interfaces gets burned,
and just the USB fails. Asus will replace the Southbridge, as
long as there is time left on the three year warranty. Since
Asus does not acknowledge this design defect, it is hard to say
if the Southbridge would be replaced after the three year
warranty has expired.
To reduce the risk of a P4Cxxx or P4Pxxx or P5P800 motherboard
failure, buy a USB2 PCI card and use the USB ports on that card,
instead of the motherboard USB ports. Use a PS/2 keyboard so you
can make changes to the BIOS. Do not use the USB ports on the
motherboard. This will reduce the risk, but cannot entirely
eliminate the risk of a failure (as the exact failure mechanism
isn't documented, and if the failure mechanism is age-related,
it could be that no workaround can prevent it from eventually
happening).
As for the P4C800-E Deluxe, it uses the 875 Northbridge. That
Northbridge has two MI 1.5 bus interfaces. One interface runs to
the Southbridge, providing 266MB/sec bandwidth for disk transfers
and the PCI bridge. The second bus interface (CSA) is private and
feeds an Intel gigabit Ethernet chip. By using a separate bus,
it means the gigabit Ethernet chip can run at gigabit speeds.
P4P800 type boards, have the Ethernet chip connected to the PCI
bus. This detail is only important if you are building a server,
as for home use, the difference in connection methods will not
normally be an issue. (For example, with Win2K, I can only get
300 megabits out of 1gigabit speed, so it doesn't matter what
bus the chip is on.)
In terms of rough generalities:
1) P4C800/P4P800 type boards.
ICH5 Southbridge. AGP port. S478 processor socket.
2) P5P800.
ICH5 Southbridge. AGP port. S775 processor socket (single core)
3) i915/i925 Northbridge based boards
ICH6 Southbridge. PCI Express video. S775 processor (single core)
4) i945/i955 Northbridge based boards
ICH7 Southbridge. PCI Express video. S775 processor (single/dual core)
No motherboard is really "future-proof" these days. PCI Express
is here to stay, so buying an AGP based motherboard means you won't
be able to tap into future video card improvements.
HTH,
Paul
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