PCI lock - always good?

Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

PCI lock is getting a lot of attention here the last couple of weeks. I'd
like to know more about it, with regards to some of the mobo/cpu combos
people are using lately. I have not used any Semprons or 64s; all the
machines I'm building are still based on the 2500+, usually the mobile
version and an NF-7/7S. I'm running the mobiles at 2.2 with multiplier
increases - rarely do I mess with clients' machines FSB. On my main machine
I've tried various things, and my NF-7 has PCI lock.

My question is, with the various FSB speeds possible, is PCI lock always
advisable, and what about AGP lock? I used to have to worry about that, but
I don't see much press on it right now.

thanks,

jakesnake
4 answers Last reply
More about lock good
  1. Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

    On Sat, 20 Nov 2004 17:41:36 +0000, jakesnake66 wrote:

    > My question is, with the various FSB speeds possible, is PCI lock always
    > advisable, and what about AGP lock? I used to have to worry about that, but
    > I don't see much press on it right now.
    >
    The nominal pci bus speed is 33.33Mhz, and double that for thre nominal
    AGP bus speed. normally, the AGP bus is derived from just doubling the
    PCI bus speed so if It's locked Then they both should stay in spec. if one
    never changes the FSB speed, or keeps it on 33MHz boundaries then a pCI
    lock really serves no purpose. Go outside the 33MHz boudaries on the FSB
    and you may end up putting the PCI/AGP buses too far over spec for the
    PCI/AGP devices to operate properly. Before the PCI lock, the other buses
    were derived from dividers. For instance, with a FSB of 100MHz a divider
    of 3 was used for the PCI bus, and the pci bus was doubled. This sets the
    pci and agp buses in spec. Now if you raise the FSB to 133 and don't
    change the 3 divider, well, you end up with a PCI bus speed of 44.4MHz and
    an AGP bus speed of 88.8MHz. You'd be hard pressed to find any pci device
    that will run reliably over 40MHz. So at 133 Mhz a 4 diver is used, and at
    166 a 5 divider and so forth. Now once you get up to 200Mhz and a 6
    divider going to 233MHz and leaving the diveider at 6 would only put the
    PCI bus at 38.8, which might be ok with some devices. So if there's no
    manual setting for the devider in the bios, you have to hope that whoever
    programed the bios had a little sense and automatically changed dividers
    to the next level midpoint into the next 33MHz boundary. Some did, some
    didn't. I've heard some didn't even program the top divider supported by
    the chipset, but i don't know this for a fact. the one thing about a PCI
    lock is that you don't have to worry about how the bios handles it. So for
    people that don't know how all this works it's great, and not too bad for
    the ones that do either.:-)

    --
    Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
    http://mysite.verizon.net/res0exft/cpu.htm
  2. Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

    "Wes Newell" <w.newell@TAKEOUTverizon.net> wrote in message
    news:pan.2004.11.20.19.25.03.405982@TAKEOUTverizon.net...
    > On Sat, 20 Nov 2004 17:41:36 +0000, jakesnake66 wrote:
    >
    > > My question is, with the various FSB speeds possible, is PCI lock always
    > > advisable, and what about AGP lock? I used to have to worry about that,
    but
    > > I don't see much press on it right now.
    > >
    > The nominal pci bus speed is 33.33Mhz, and double that for thre nominal
    > AGP bus speed. normally, the AGP bus is derived from just doubling the
    > PCI bus speed so if It's locked Then they both should stay in spec. if one
    > never changes the FSB speed, or keeps it on 33MHz boundaries then a pCI
    > lock really serves no purpose. Go outside the 33MHz boudaries on the FSB
    > and you may end up putting the PCI/AGP buses too far over spec for the
    > PCI/AGP devices to operate properly. Before the PCI lock, the other buses
    > were derived from dividers. For instance, with a FSB of 100MHz a divider
    > of 3 was used for the PCI bus, and the pci bus was doubled. This sets the
    > pci and agp buses in spec. Now if you raise the FSB to 133 and don't
    > change the 3 divider, well, you end up with a PCI bus speed of 44.4MHz and
    > an AGP bus speed of 88.8MHz. You'd be hard pressed to find any pci device
    > that will run reliably over 40MHz. So at 133 Mhz a 4 diver is used, and at
    > 166 a 5 divider and so forth. Now once you get up to 200Mhz and a 6
    > divider going to 233MHz and leaving the diveider at 6 would only put the
    > PCI bus at 38.8, which might be ok with some devices. So if there's no
    > manual setting for the devider in the bios, you have to hope that whoever
    > programed the bios had a little sense and automatically changed dividers
    > to the next level midpoint into the next 33MHz boundary. Some did, some
    > didn't. I've heard some didn't even program the top divider supported by
    > the chipset, but i don't know this for a fact. the one thing about a PCI
    > lock is that you don't have to worry about how the bios handles it. So for
    > people that don't know how all this works it's great, and not too bad for
    > the ones that do either.:-)
    >
    > --
    > Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
    > http://mysite.verizon.net/res0exft/cpu.htm

    Thank you for the excellent explanation. I really appreciate it . . .
    especially since you've probably explained it 100 here for guys like me :)
    The other question I meant to ask is, how do you know a board has PCI lock
    prior to buying it? I think all of the recent Abit boards I've purchased
    offered PCI lock, but I didn't know it beforehand. I don't recall ever
    seeing it in product descriptions.

    thanks,

    jakesnake
  3. Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

    On Sun, 21 Nov 2004 14:43:24 +0000, jakesnake66 wrote:

    > Thank you for the excellent explanation. I really appreciate it . . .
    > especially since you've probably explained it 100 here for guys like me :)
    > The other question I meant to ask is, how do you know a board has PCI lock
    > prior to buying it? I think all of the recent Abit boards I've purchased
    > offered PCI lock, but I didn't know it beforehand. I don't recall ever
    > seeing it in product descriptions.
    >
    DL the board manual before purchasing. You should be able to find out
    about all you want from that. Then also search for reviews on the board.

    --
    Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
    http://mysite.verizon.net/res0exft/cpu.htm
  4. Archived from groups: alt.comp.hardware.overclocking.amd (More info?)

    jakesnake66 wrote:

    >
    >
    > Thank you for the excellent explanation. I really appreciate it . . .
    > especially since you've probably explained it 100 here for guys like me :)
    > The other question I meant to ask is, how do you know a board has PCI lock
    > prior to buying it? I think all of the recent Abit boards I've purchased
    > offered PCI lock, but I didn't know it beforehand. I don't recall ever
    > seeing it in product descriptions.
    >
    > thanks,
    >
    > jakesnake


    All mainboards with nForce2 has PCI Lock. KT880 has it too. that's the
    only Socket A chipsets with PCI Lock. On AMD64 most new K8T800 PRO has
    it and ALL nForce3 250.
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