PCI-X primer or overview

  • Thread starter Thread starter Grant Schoep
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Grant Schoep

Hey all, I'm trying to get back up to speed with current technoologies. One
thing I am a bit muddle on yet is the new PCI-X or PCI express bus, that
newer motherboards are coming out with. I know some general info about it,
but I would love to find some good articles somewhere on the net to give me
a better "feel" for it. I know there are 1x 4x 16x, sometimes multiple 16x
for dual graphics cards and other devices.

Basically, I just would like to find some good articles introducing the
technology to make sure I really understand it.

One other general question. Is PCI-X and PCI express the same thing? I
think I remember reading something a month back that was saying they were
different.

Thanks
 
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One other general question. Is PCI-X and PCI express the same thing?
Click to expand...

No. PCI-X has been around longer; it's an extension of the original PCI
that, depending on how it's implemented, allows up to 8x the bandwidth of
PCI (instead of a 32-bit bus at 33 MHz, you can have a 64-bit bus running at
133 MHz). It never really caught on in desktop systems (they didn't really
need the bandwidth anyway), but you'll find it in servers and some
workstations. PCI Express is a newer specification that uses serial
communication at high speeds to deliver more bandwidth than PCI (I'm a bit
fuzzy on the exact numbers for PCI Express, as I've only built one box at
work that uses it). While PCI-X augments PCI, PCI Express aims to
eventually replace PCI.

_/_
/ v \ Scott Alfter (remove the obvious to send mail)
(IIGS( http://alfter.us/ Top-posting!
\_^_/ rm -rf /bin/laden >What's the most annoying thing on Usenet?

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Scott Alfter said:
133 MHz). It never really caught on in desktop systems (they didn't really
need the bandwidth anyway), but you'll find it in servers and some
Click to expand...

Less that they "didn't need the bandwidth" than that they didn't need the
bandwidth for anything except video cards, and AGP already handled those
cheaper.
communication at high speeds to deliver more bandwidth than PCI (I'm a bit
fuzzy on the exact numbers for PCI Express, as I've only built one box at
work that uses it). While PCI-X augments PCI, PCI Express aims to
eventually replace PCI.
Click to expand...

IIRC, PCI-E 4X = ~1GB/sec or roughly the bandwidth of PCI-X/133mhz; PCI-E
8X, which seems to be the standard for server class peripherals, = ~2GB/sec,
and 16X which is pretty much just for video cards = ~4GB/sec.
 
Hey all, I'm trying to get back up to speed with current technoologies. One
thing I am a bit muddle on yet is the new PCI-X or PCI express bus, that
newer motherboards are coming out with. I know some general info about it,
but I would love to find some good articles somewhere on the net to give me
a better "feel" for it. I know there are 1x 4x 16x, sometimes multiple 16x
for dual graphics cards and other devices.

Basically, I just would like to find some good articles introducing the
technology to make sure I really understand it.
Click to expand...

Start at www.pcisig.org but you'll find that, like PCI, full specs are only
available to paying members. Then try
http://www.intel.com/technology/pciexpress/devnet/desktop.htm Beyond
that... Google.
 
Nate said:
Less that they "didn't need the bandwidth" than that they didn't need the
bandwidth for anything except video cards, and AGP already handled those
cheaper.




IIRC, PCI-E 4X = ~1GB/sec or roughly the bandwidth of PCI-X/133mhz; PCI-E
8X, which seems to be the standard for server class peripherals, = ~2GB/sec,
and 16X which is pretty much just for video cards = ~4GB/sec.
Click to expand...

PCI-E 4X is indeed 1 GB/s. However, that is *each* way, so the 1
GB/s bandwidth of PCI-X/133MHz is effectively only half as much
in many circumstances.

PCI-E 4X, not 8X, is what is so far being used for early versions
of PCI-E server peripherals, including RAID cards and Gigabit
NICs. It takes a pretty big RAID array to eat up 1 GB/s, so 4x
slots should do quite nicely for a while. Note also that a PCI-E
slot isn't sharing bandwidth with other slots - unlike PCI and
PCI-X where there are usually several slots on a single bus.

PCI-E 8X so far appears to be used for little but video cards,
and even then it is always a slot in 16X form factor but only
wired for 8X.

The only PCI-E 1X devices I have heard of have been NICs, SATA
cards, and cards for additional USB or FireWire ports. I talked
to someone at Creative a few months ago and he refused to even
speculate on what size slot Creative's first PCI-E sound cards
would use, but 1X sounds about right to me.

I have heard that Intel was working on an 8X or 16X Infiniband
device. Would love to know more if anyone has a link to some
solid info. I searched Intel's site a couple of months ago and
turned up nothing.
 
Grant said:
Hey all, I'm trying to get back up to speed with current technoologies. One
thing I am a bit muddle on yet is the new PCI-X or PCI express bus, that
newer motherboards are coming out with. I know some general info about it,
but I would love to find some good articles somewhere on the net to give me
a better "feel" for it. I know there are 1x 4x 16x, sometimes multiple 16x
for dual graphics cards and other devices.

Basically, I just would like to find some good articles introducing the
technology to make sure I really understand it.

One other general question. Is PCI-X and PCI express the same thing? I
think I remember reading something a month back that was saying they were
different.

Thanks
Click to expand...

Go to www.askjeeves.com and type in "What is PCI Express?".

I'll bet dollars to donuts that you find info sources of the sort
you are looking for.
 
Rob Stow said:
PCI-E 8X so far appears to be used for little but video cards,
and even then it is always a slot in 16X form factor but only
wired for 8X.
Click to expand...

Infiniband cards as well, from my past job. I had been under the impression
that the PCI-E SCSI RAID cards I'd been looking at were 8X as well but I may
well be mistaken.
 
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