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PCI Express - Coming Soon to a PC Near You

Max Romantschuk writes "I've been following the emerging of PCI Express for some time now. PCI Express, previously known as "Third Generation I/O" or "3GIO", is the technology set to replace PCI. PCI has been with us for around ten years now, and is rapidly running out of bandwidth. Last week Anandtech ran an interresting story on PCI Express. The techology has previously been covered by Hexus and ExtremeTech aswell. I feel this technology looks all set to replace PCI, and we really do need some new bus technology to keep up with the bandwidth demands of today's applications. Or is this just yet another way to force us into a new upgrade cycle?"

24 of 359 comments (clear)

  1. It will not just replace PCI by motown · · Score: 5, Informative

    Due to its high bandwidth, it's expected to replace AGP as well.

    --
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    1. Re:It will not just replace PCI by merlin_jim · · Score: 5, Funny

      Due to its high bandwidth, it's expected to replace AGP as well.

      This is not technically true, though I can see why you would be confused.

      They anticipate that customer demand for PCI-X will be so great that it will be difficult to sell AGP boards, therefore AGP will be renamed PCI-X. In order to distinguish between the two, the PCI-X spec will be designated "PCI-X High Speed" while the AGP spec will be designated "PCI-X Full Speed"

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    2. Re:It will not just replace PCI by Fulcrum+of+Evil · · Score: 5, Funny

      the PCI-X spec will be designated "PCI-X High Speed" while the AGP spec will be designated "PCI-X Full Speed"

      The really terrible thing here is that I can't tell if you're being serious or not.

      --
      "We returned the General to El Salvador, or maybe Guatemala, it's difficult to tell from 10,000 feet"
  2. PCI 2 is the same as PCI? by tekrat · · Score: 4, Funny

    Just wait until the PCI group renames PCI Express to PCI just to keep things confusing to the consumer. After all, if consumers are demanding PCI Express in their computers, then just rename everything to PCI express... or however that USB fiasco works out....

    I'm just wonering now if that external HD USB2 case I bought is really 1.1 or not... Grrrrr.

    --
    If telephones are outlawed, then only outlaws will have telephones.
  3. Hmmm by koh · · Score: 4, Interesting

    Or is this just yet another way to force us into a new upgrade cycle?

    Or maybe current PCI devices don't support DRM out of the box ? Please upgrade your bus techno, so we can use all this extra bandwidth to transfer huge crypto keys to/from your hardware, just in case you want to play a copyrighted sample on your soundcard :)

    (-1 Paranoid)

    --
    Karma cannot be described by words alone.
  4. Does PCI Express solve the shared IRQ problem? by WeiszNet · · Score: 5, Insightful

    More than bandwidth, what I need would be a bus
    that doesn't have a problem with too many extensions
    because of a limited number of IRQs.

    Today most mainboard come with many onboard PCI componentes. If you really are going to put in 3-5 extra PCI components in a stock PC, you usually end up in a nice game of 'let's see what order works best', or cannot use all cards together at all.

    1. Re:Does PCI Express solve the shared IRQ problem? by arth1 · · Score: 4, Informative

      The limited number of IRQs hasn't been a problem since PCI 2.1 and APIC. It's a problem with Windows 9x and a few other operating systems, but those won't be able to use PCI Express anyhow.

      The problem today is more with interrupt line sharing (#A, #B, #C, #D -- some motherboards add more, but four is the old spec), and cards sharing the actual interrupt and not the interrupt queue (IRQ), depending on how you place them.

      But yes, to answer your question, there's less problems, due to the parallel serial nature (now is that an oxymoron?) of the controller interface, working somewhat like SCSI does.
      At least until 4x, 8x and 16x PCI Express arrives in force, and cards starts competing and assuming that all the streams are available for THEIR card, much like some cards today think it's ok to bump up the PCI latency, cause the user SURELY must have some unpopulated slots we can steal time from...
      Yeah, when that happens, it may be hell to troubleshoot, but we'll just wait and see...

  5. About time by zensonic · · Score: 4, Insightful

    Given that the PCI interface was introduced to the world by intel in 1992 and that we since have increased the cpu processing powers by a hundred fold (give or take a little) it is really about time that the bus catches up.

    --
    Thomas S. Iversen
  6. Re:Say goodbye to legacy crap by Surak · · Score: 4, Funny

    Better yet, let's rename PCI to PCI-Express and keep PCI-Express as PCI-Express, and then we'll all have PCI-Express. ;)

  7. A reasonable upgrade cycle by brucmack · · Score: 5, Interesting

    I'd say a new standard every 10 years is a pretty reasonably upgrade cycle compared to most other PC technologies...

    OK, so yes we can probably live with PCI for longer (possibly much longer), but why not introduce a new standard with better potential? It maintains complete backwards compatability with regular PCI components, so manufacturers of harware don't even have to change anything. Of course another issue is motherboard cost, but there will always be new features put into successive motherboard generations that aren't in widespread use yet... like serial ATA, gigabit ethernet, etc. And there will probably be motherboards available for a lower cost without those features as well.

  8. Re:Speed by ViXX0r · · Score: 5, Informative

    As I understand it, using serial there is no having to worry about whether all the bits arrive at the same time (as there obviously is with parallel), and so the speed of transmission can be dramatically increased past the point at which it becomes faster than the "equivalent" parallel technology... bits arrive in the order they were sent - guaranteed.

    --
    University - a box of academia nuts.
  9. Re:Speed by KrishnaACD · · Score: 5, Informative
    I wondered this too, so went digging. the most concise and, to me, most credible answer was the following (Credit to K. Adam's at Geek.com)
    Serial Faster than Parallel... (5:41pm EST Wed Jul 25 2001) The problem with parallel (ribbon) data transfer cables is the crosstalk that occurs between adjacent conductors at very high clock/transfer speeds. IBM developed a work-around for ATA-66 and ATA-100 by using an 80-conductor cable with a 40-pin interface, by stringing a "ground" conductor between each "signal" conductor. Capacitance issues, "standing waves," and impedance (electrical resistance as relates to rapidly-changing voltages) matching problems become more evident in parallel (ribbon) cables as you crank up the clock/transfer speeds, also. It's a lot easier to match the impedance of a few conductors in a serial cable to its interface, than trying to match impedance for 40 conductors. Parallel schemes actually have a lot less "processing" overhead than serial schemes, but you're ultimately limited by physics a lot more quickly than with serial... - by K. Adams
    Kacd.
  10. Physical Connector by CaseyB · · Score: 4, Funny
    I'm a bit concerned about the way the cards are mounted. System bus connectors aren't just data connections -- they're structural foundations for today's giant hardware.

    How are those tiny little serial connectors supposed to support the weight of my 2007 GeForce Maxx Fury 7 video blaster with its jet turbine fan? They'll snap like twigs, I tell ya!

  11. What upgrade cycle? by simong_oz · · Score: 5, Insightful

    Or is this just another way to force an upgrade cycle?

    It may well be one of the intentions of it, but one thing I don't get is that with CPU speeds and hard disk capacities where they are now, the average computer buyer (which probably is not very well represented on slashdot) no longer really needs to upgrade their computer, so changing interface/slot shape/etc won't really matter to them.

    I know I'm generalising, but the only applications that really push today's computers are games (and high end scientific programs, but they're a fairly minor special case) and I would guess that most computers are not used primarily for games (ie. "serious gamers" - think families). Serious gamers will always be upgrading their computer to the latest and greatest anyway - they don't need to be forced into an upgrade cycle.

    It's getting to the point now where by the time the average family decides they need to upgrade their computer, it is easier (and maybe even cheaper) to just buy the latest middle-of-the-line computer package.

    I'd almost question whether the idea whole idea of upgrading is itself becoming obsolete for an average computer user?

    --
    "Because it's there." - George Mallory, when asked why he wanted to climb Mt Everest, March 18, 1923 (New York Times)
  12. User-facing bus losing importance by IGnatius+T+Foobar · · Score: 4, Interesting

    Based on the direction in which mass-market computers are moving, the bus that gets exposed to the user is getting somewhat less important. Aside from gamers and tinkerers, and people who manage big servers, how many computer users ever have a need to open up the case?

    Ten years ago it was almost a given that at some point, you (or your Computer Guy) had to add or replace one of the cards -- add Ethernet, upgrade the video, whatever. Nowadays, the hardware on-board is more than sufficient, and any of those "special" accessories you get, such as storage drives for your digital camera, or a scanner, or whatever, are more likely than not going to be USB or FireWire.

    It's very likely that the mainstream desktop computer is going to move to a slotless "brick" form factor. This would have the side benefit of making it much cheaper. This form factor is available already, but it's not yet cheap because it's still considered a "specialty" unit.

    I'd also be happy to see the return of the Commodore 64 form factor -- just shove everything into the keyboard. Plug in your mouse and monitor and Ethernet, and go.

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  13. Re:Is HDTV the only application? by imsabbel · · Score: 5, Interesting

    One high end hard disc delivers 50MB+/s.
    One gigabit Ethernet card can do >80MB/s
    Together they are limited by PCI.
    Now try Raid, TV-Card with PCI-OVerlay, GFX-Cards (Yes, they need a few 100MB/s)...

    Plus remember that you NEVER EVER reach 133 MB/S with PCI. Even a single device can be happy to get 110MB with long bursts, and if you have many devices, effective total bandwith is more like 66 than 133 MB/s.

    --
    HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
  14. Re:Rapidly running out of bandwidth? by hbackert · · Score: 4, Informative

    Now that's a no-brainer.

    My computer is by far not a high-end box, but PCI is a (small) bottle-neck, even for me.

    Let's see: 2 IDE channels, 2 disks, that's 50 MB/s each, 1 GBit network, that's peak 100MB/s. A U2W SCSI host adapter with 1 single, very fast disk is good for 70MB/s. Then there is USB2 (everything is USB2 now) and Firewire (each 50MB/s). Adds up to (peak) 370MB/s.

    You and me and most people know, that a usual user and most unusual users like the ./ crows will never use all devices at once. But just copying data from disk to network saturates the bus.

    A simple fix is 66MHz 64Bit PCI, but those are very rare in consumer machines. So while PCI-Express might be currently overkill, I doubt simple 33MHz 32Bit PCI will be sufficient even for consumer grade computers. Just imagine 10 years ago when PCI started: most were using ISA and that was enough for most usual users. 10MBit/s Ethernet cards used less than 1MB/s. Who needs a faster bus? Only servers needed PCI (or EISA).

    Watching the long migration from ISA to PCI until ISA was (mostly) replaced, I don't expect PCI-Express to replace PCI within 5 years. And in 5 years I would bet, that PCI looks like ISA does now: slow and outdated.

  15. Parallel faster than Serial by gorjusborg · · Score: 5, Informative

    using serial there is no having to worry about whether all the bits arrive at the same time (as there obviously is with parallel), and so the speed of transmission can be dramatically increased past the point at which it becomes faster than the "equivalent" parallel technology... bits arrive in the order they were sent - guaranteed.

    I'm afraid this might add to the confusion about serial interfaces being 'faster' than parallel. While it is true that you don't have to worry about data/clock skew when using serial interfaces, enabling you to clock them faster, a parallel interface running at the same clock speed as a serial interface will always be faster in terms of data throughput. The reason for this is simple: serial == 1 bit per clock, parallel = > 1 bit per clock.

    So, saying that serial is faster than the "equivalent" parallel interface is confusing, and incorrect, because one could be referring to equivalent clock rates being used for each interface, in which case parallel will provide at least twice the data throughput. On the other hand, "equivalent" could be referring to identical throughput rates, in which case the serial and parallel interfaces would provide, by definition, identical data rates.

    The real advantage that PCI Express has over PCI/PCI-X is that it is a point-to-point, rather than a multi-drop, bus. This setup requires less time between pin transitions, meaning that it can be clock faster. Also, like Ethernet, a serial protocol can imbed the clock into the data stream so clock/data skew is no problem whatsoever.

    Serial is not better than parallel anymore than digital is better than analog, there are just physical reasons why implementing point-to-point serial at significantly higher clock rates is easier than multi-drop parallel.

    Anyone still awake?
    Didn't think so :-l

    --
    If it's not one thing, it's Steve's Mother
    1. Re:Parallel faster than Serial by jmichaelg · · Score: 4, Informative

      Which is why PCI Express is specified as a scaleable technology. You can get single pin X1, dual pin X2, quad pin X4, and so on.

      Need more bandwidith - add more pins. With each pin delivering 100 megabytes, there's lots of room to grow.

  16. Well, of course. PCI isn't fast enough. Or is it? by foxtrot · · Score: 4, Informative

    We realized PCI wasn't going to be fast enough years ago-- that's why pretty much every motherboard you can buy today has an AGP socket.

    And even that wasn't fast enough, now we have AGP 8x.

    But seriously, is PCI really not fast enough for the general consumer, once he's got an AGP socket? PCI that runs on a 66MHz bus that's 64 bits wide has existed and even been available in high-end PC class hardware for years, but few of even Slashdotters have anything other than 32 bit 33MHz PCI in our home machines. The only time I ever deal with the 64 bit PCI cards is for Sun Microsystems hardware at the office.

    I don't think this is "forcing another upgrade cycle" at all-- upgrades already exist, and most of us don't have 'em.

  17. No use. The well has been poisoned. by JCCyC · · Score: 4, Insightful

    Never again will any announcement of new hardware technology be received by us geeks with the glee it once was. The only thing that comes to our minds now is "great, another opportunity for them to add DRM and phase out hardware that allows copying"

  18. Re:Why? by dissy · · Score: 4, Insightful

    > What PCI device are you using that is bandwidth limited & will benefit
    > from a faster PCI bus?

    Gigabit ethernet, soon 10gbit ethernet..
    multiple firewire buses, or even one firewire 800 bus..
    Multiple high speed graphics cards..
    Multiple SCSI or fiberchannel buses..

    > I don't have anything.

    > I really have nothing that will gain any benefit.

    Well thank you for deciding that what you need is exactly what everyone else needs and they should be happy with that :P

  19. Re:Rapidly running out of bandwidth? by captaineo · · Score: 4, Informative

    The one consumer-level application where a better bus is vital is HDTV. Current buses are just barely able to handle uncompressed SDTV (20-30MB/sec). (in theory PCI gives you 133MB/sec and AGP more, but as they say, in theory there is no difference between theory and practice :).

    PCI-X will finally bring HDTV (~200MB/sec) within reach. What this means is that you'll be able to have a software-only HDTV decoder - which will make it trivial to receive HDTV broadcasts on a PC, and make HD-DVD players possible.

    At the pro level, this is just about the last thing that a $50K SGI system has over a cheap Linux PC - playback and maniupulation of uncompressed HDTV video. It's about time PCs finally caught up to "workstations" in the bus department...

  20. Re:Is this what the consumers want or... by virtual_mps · · Score: 4, Informative
    Go out and get a firewire controller.
    Right there you have almost 3 times the bandwidth of a SCSI controller, and 4 times the bandwidth of an ata100 IDE controller.

    Moderators on crack. This is just plain wrong. Firewire is 400 or 800 Mbits/s, while SCSI is up to 320 Mbyte/s, IDE is up to 133 MByte/s, and Fibre Channel is up to 250 Mbyte/s. These numbers are directly comparable, because different buses have different amounts of overhead, but for sure firewire is a slow also-ran when talking only about performance. (When talking about cost, flexibility, etc., firewire looks better, of course.) As far as PCI goes, the top end is over 1 Gbyte/s, which is a bottleneck for some applications, but not firewire. Also, in high-end servers you'll have a number of pci buses to improve performance.