pci-e questions

TexTex Dallas/Ft. Worth
edited August 2005 in Hardware
Ok most chipsets keep referring to these as for video. I have a raid controller meant to run in a 8x pci-e slot.

Is this something that they just expect it to be a video card or are there incompatibilities in these early chipsets?

Most the slots seem to be either 1x or 16x. Will a 16x slot back down to 8x?

Need info ! Crap where is thrax when you need him?

Tex

Comments

  • ThraxThrax 🐌 Austin, TX Icrontian
    edited February 2005
    1x, 2x, 8x and 16x PCIe slots are designed for every future card, much like PCI was designed to replace ISA. Video, RAID, sound, LAN, you name it, PCIe was designed with that application in mind.

    Now, the true PCIe specification calls for the slots of various bandwidths to also be various sizes. The 8x should be smaller than the 16x, however SLI turns 16x-sized slots into 8x channels, so that point is made somewhat insignificant.

    Ultimately, the card <i>should</i> work, as there's no reason for it not to.
  • mmonninmmonnin Centreville, VA
    edited February 2005
    So they are "Backwards compatible"...meaning a 1x could work in any PCIx slot? I think thats what Tex was asking and I would like to know as well. It would make sense.
  • ThraxThrax 🐌 Austin, TX Icrontian
    edited February 2005
    As far as I know, they're upwards compatible. A 1x card will fit in any PCIe slot, a 4x in a 4/8/16, an 8 in an 8/16, and a 16 only in a sixteen.

    I may have read the standards wrong, but I'm pretty sure that's how that works.
  • TexTex Dallas/Ft. Worth
    edited February 2005
    I don't care about the 1x at all. I have a hotrod raid controller that is supposed to work in a 8x pci-e slot. But all the MB's are running 16x pci-e slots not 8x.

    Tex
  • ThraxThrax 🐌 Austin, TX Icrontian
    edited February 2005
    Thrax wrote:
    They're upwards compatible... A 1x card will fit in any PCIe slot .... an 8 in an 8/16
  • MediaManMediaMan Powered by loose parts.
    edited February 2005
    PCI Extended (PCI-X) is meant to be backwards compatible with regular PCI slots. Therefore a PCIx capable card can or should theoretically work in a regular PCI board but the limit is the 33 MHz bus speed.

    PCIx boards are supposed to be upwards of 1 Gbps on the bus.

    PCIx is the new and improved version of PCI...call it a turbocharged overhauled PCI bus system. It does things like double pump etc. Much like RAM is doing now to squeeze more performance.


    PCI Express (PCIe)...if I got this correct...works hand in hand with AMD's HyperTransport. PCIe was formerly known as 3GIO which I think Intel heavily backed.

    PCIe is "next gen" improving upon PCI-X.

    Now...I don't think PCIe is backwards compatible with anything like PCIx is with PCI since it's "new" technology. PCIx uses "lanes" for data hence the 1x and 2x terms (1 lane and 2 lanes for bidirectional data)...up to a maximum of 2.5 Gbps bandwidth.

    PCIe is better than PCIx on paper.
  • Omega65Omega65 Philadelphia, Pa
    edited February 2005
    You should be able to drop in a PCI video card and use the PCie 16x slot for the raid controller
  • TexTex Dallas/Ft. Worth
    edited March 2005
    I have pci-x raid controllers that will not work at all in any other type of 64 or 32bit slot. They are pci-x or nothing.

    I have run older 64bit/66mhz cards in a pci-x slot. so the slot is backwards compatible but not all pci-x cards will work in a older slot even another 64bit slot.

    That make sense?

    Tex
  • jukkjukk
    edited March 2005
    What I've read about PCI-e it's a serial communication bus (I'm an electrical/software engineer so I am supposed to know what it means LOL). Tom's hardware had an article about PCI-e. An 8x card should work fine in a 16x slot. It just doesn't use the 8x lines left.
  • TexTex Dallas/Ft. Worth
    edited March 2005
    I just paid for the controller so I hope so. (long sigh....)

    Tex
  • jukkjukk
    edited March 2005
    Here is a white paper from Dell on the PCI Express standard. Scroll down to Table 3. It clearly states that an 8x card is allowed in a 16x slot. http://www1.us.dell.com/content/topics/global.aspx/vectors/en/2004_pciexpress?c=us&l=en&s=corp

    8x PCI Express is a very fast interface. The interface is full duplex so in theory there are 4 GigaByte/s bandwidth (2 GB/s each way). On a RAID card it's meaningful to talk about the total bandwidth, but with for instance 16x graphics cards it's meaningless to mention 8GB/s because a graphic card only transfers data one way, using only max 4GB/s.
  • Straight_ManStraight_Man Geeky, in my own way Naples, FL Icrontian
    edited August 2005
    Tex wrote:
    I have pci-x raid controllers that will not work at all in any other type of 64 or 32bit slot. They are pci-x or nothing.

    I have run older 64bit/66mhz cards in a pci-x slot. so the slot is backwards compatible but not all pci-x cards will work in a older slot even another 64bit slot.

    That make sense?

    Tex

    Yes, some cards will not function at slow speeds. Thus, they may be hard-wired for PCI-x only as far as bandwidth requirements to operate right-- quite a few cards tuned for speed and flow width specifically DO exist. That is why Tyan makes mixed data media bandwidth PCI-X and PCI boards.

    Codicils:

    I have not looked for a triple PCI-e, PCI-x, PCI board from them recently, do not know about that. Have not looked for a PCI-e plus PCI-x board either, lately.
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