1 x PCI Express 2.0 x16 slots (@x4 mode, 2.5GT/s)"

What does "1 x PCI Express 2.0 x16 slots (@x4 mode, 2.5GT/s)" mean?

Here is the link to my motherboard.

ASUS P7P55D LGA 1156 Intel P55 ATX Intel Motherboard - Retail

Thanks
7 answers Last reply
More about express slots mode
  1. ^ That slot can only operate at x4 mode(Speed)
    For eg. when you put a graphics in that slot, it would operate at a lower speed because that slot provides lower bandwidth...
  2. As gkay09 said, it offers lower bandwidth, equivalent to a x8 PCI-E 1.1; you probably don't want to use it for graphics, but it would be fine for a RAID card.
  3. About graphics bandwidth:
    They just did an detailed review to see what difference Intel's latest offerings would be because the newest CPU has built-in PCIe management but can only do 1xPCIe x16 v2.0 or 2xPCIe x8 v2.0.

    The new ATI card, the HD5870 (currently the fastest single GPU card for desktop gaming) was used and it was determined that the x8 interface was NOT slowing it down). There is actually about a 1% difference but in reality you'd either be using the full single x16 or two in Crossfire but the bandwidth requirements in Crossfire aren't 2x (even in the CPU can keep up). So for the latest batch of video cards 1x16 or 2x8 (v2.0) for the PCI-Express bus is fast enough.

    There is a lot of bandwidth in a slot even at "only" 4x PCIe v2.0. You can safely handle at LEAST a card with half the bandwidth (the frame rate is a rough guide) of the HD5870 which is the HD4870 or equivalent NVidia.
  4. Update:

    I'm not sure where you got your "x4" information. By all account this is an excellent board that offers:
    1) 1xPCIe x16, or
    2) 2x PCIe x8

    Since the PCIe Controller is in the actual CPU this can't really change. This board can handle a Crossfire of 2x HD5870 1GB cards with no bandwidth restrictions.
  5. photonboy said:
    Update:

    I'm not sure where you got your "x4" information. By all account this is an excellent board that offers:
    1) 1xPCIe x16, or
    2) 2x PCIe x8

    Since the PCIe Controller is in the actual CPU this can't really change. This board can handle a Crossfire of 2x HD5870 1GB cards with no bandwidth restrictions.


    While its true that the CPU controls the PCI-E lanes, the second slot has an electrical restriction which only allows it to run 4 lanes; it will slow a 5870 a bit, but probably not enough that you'd notice.
  6. Just for fun, looks like these are all good answers. The real question lies in where you saw the information, obviously you used a utility that looks at your system and provides a report. Relying on Photonboys report about motherboard properties specific to your board I see Two possibilites. The utility your using is not current enough to see the real connection level. Your using another pci-xpress device which is eating up the available lanes which could downgrade the lanes available and or there is insufficient power getting the your video card which could force it to downgrade it's connection level. If you use CPUZ it will tell you whether your video connection is running in 16 lanes, 8 lanes or 4 lanes by clicking on ?motherboard tab.
  7. Its listed on the spec page of the mobo he's looking (link in the OP).
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