PCI latency? a Q for Gurus

Discussion in 'Links' started by Emile, Jan 6, 2005.

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  1. VisitorX

    VisitorX Member

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    hi i have a question which settings is good for me with an nvidia 9800 gtx + ??
     
  2. killerxr290

    killerxr290 Banned

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    lol

    PCI-E cards dont have any latency timers. So you cant change your PCIE latency, PCI you can but your video card is PCIE so it would be pointless
     
  3. VisitorX

    VisitorX Member

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    Thanks for answer...

    for what i have the settings in bios menu.. i changed it to 128 and now 3d applications run a lil better..

    it meens equal which settings i do its pointless ??
     
  4. deltatux

    deltatux Ancient Guru

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    PCI latency is basically just how much time you allow the PCI bus controller to allow each device to master the bus. Since the PCI bus is basically a Time-Division Multiple Access (TDMA) technology, each device gets a slice of time to the full bandwidth before it has to give up the bandwidth channel for the next device.

    You don't get this with PCI Express because it's not a bus system, it's a point-to-point interconnect, all devices gets its dedicated lanes and NEVER share resources. Thus, having a latency setting is quite useless since there's nothing to share.

    What VisitorX experienced is probably a placebo effect caused by the switch.

    deltatux
     

  5. TruMutton_200Hz

    TruMutton_200Hz Ancient Guru

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    PCIe data transfer is packet based so latency still matters to some devices (such as graphics cards and soundcards) but not to all devices. The real reason why PCIe has no latency setting is because the system handles device priorization automatically.
     
  6. deltatux

    deltatux Ancient Guru

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    PCIe latency in terms of packets are too small to detect to the point where a PCI latency switch would affect any device. Many devices that do require low latency works very well on the interconnect without any special tweaks to the interconnect.

    This is not true with PCI since there's the whole bus mastering latency.

    deltatux
     
  7. TruMutton_200Hz

    TruMutton_200Hz Ancient Guru

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    Then please explain why device priorization is part of the PCIe design.
     
  8. deltatux

    deltatux Ancient Guru

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    Personally, I have no clue, from what I've learned through reading hardware articles is that PCIe doesn't share its resources with other devices. My guess here would be because the software layer is the same as the older PCI so for software, the prioritization is required so traffic for PCIe devices that are sensitive gets priority in the software layer.

    deltatux
     
  9. TruMutton_200Hz

    TruMutton_200Hz Ancient Guru

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  10. churlock

    churlock New Member

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    This worked for me (posted by "Goodtwist" on another forum):

    Simply let Windows 7 deal with the problem by pressing "Troubleshoot compatibility" in the context menu, while holding your mouse on the installation file.

    What turns out to be the problem - Windows denying you to install PCI Latency Tool due to lacking admin authority - is a missing digital signature of the PCI Latency Tool Config Space Access Driver (in LtcyWDM.sys).


    This advice should be posted under the instructions for the PCI Latency Timer app as a lot of people are having an issue trying to load under win 7.
     

  11. BetA

    BetA Ancient Guru

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    wait, is that tool actually usefull for me? even i have pci express? or isnt it just for agp cards etc..like in the old days..
    i thought nowadays u dont have to worry about this anymore..

    can someone please help me out here?

    -BetA-
     
  12. Mineria

    Mineria Ancient Guru

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    Doubt that it will do anything for your system, the app is old (not updated since December 2005) so shouldn't be used on modern systems.
    Also changing from default values can give sync problems, had that with some recording software in the old days, it did help with some games back then thou.
     
  13. Halmeth

    Halmeth New Member

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    Sups all... I know this is a tremendous old thread, and a tremendous old software... But i'm already using an old computer with an old AGP card (Geforce 7800 GS AGP) My issue is the next: When I play Source (valve) Games I get that stressful issue of crash to desktop with looping sound... Maybe this PCI Latency Tool can be useful for my old-lady machine... what are the best settings to get a good perfomance gaming on CS Source or Day Of Defeat Source?...

    Thanks all...
     
  14. omnihova

    omnihova New Member

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    Pretty sure most windows versions have a setting to accept non digitally signed drivers. Just search for how to do it for your windows installation if you really want to install that software. There is a newer latency tool under top downloads called sisoft sandra you might try as well.
     
  15. theoneofgod

    theoneofgod Ancient Guru

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    Test Mode.

    Code:
    Enable:
    
    bcdedit.exe -set loadoptions DDISABLE_INTEGRITY_CHECKS
    bcdedit.exe -set TESTSIGNING ON
    
    Disable:
    
    bcdedit.exe -set loadoptions DENABLE_INTEGRITY_CHECKS
    bcdedit.exe -set TESTSIGNING OFF
     

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