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Thread: AGP 8x voltage

  1. #1
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    AGP 8x voltage

    My mobo is a Asus P4G8X and it has an AGP Pro 8x slot. There is a page about this, and it says:
    ! Install only 1.5V AGP cards on this motherboard!
    But WTF! I thought AGP 8x used 0.8V!
    AGP Pro is just a little extra bit on the end of the slot, 90% of cards dont even touch it.
    There is a warning led on the mobo that lights up and prevents the comp from booting if you install a 3.3V card, but nothing is said about the 0.8V.
    Is this a mistake in the manual? Can it really use 0.8V? Or can it not?


  2. #2
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    http://www.hothardware.com/hh_files/...us_p4g8x.shtml
    According to this site, i can use 0.8V AGP 8x cards

    But also, my mobo only has PC2100 Ram support, yet i have PC2700 installed. It runs fine. Am i supposed to be able to put higher rated ram in my system? I fink i am, but just checking.
    Memory aint my strong point, gaining knowlege on the subject tho

    But now i have a few different opinions on what my mobo can handle.
    Manual says: ONLY 1.5V
    I think: BUT AGP 8X USES 0.8V
    Some other websites say: AGP 8X ONLY USES 0.8V, UNIVERSAL USES 1.5V AND 0.8V (my mobo is universal agp) AND AGP 4X ONLY USES 1.5V

    Weird
    http://www.ati.com/support/faq/agpchart.html

  3. #3
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    Confused? That's because many are talking, and few know what they're talking about.

    Voltages on AGP.

    Card supply voltage is always 3.3V.

    Signalling voltage is 3.3V on 1x/2x modes, and 1.5V on 4x/8x modes. 8x uses a reduced voltage swing of 0.8V.

    By how things are defined in the AGP 3.0 specification, 8x cards and boards must always also support 4x.

    Questions?

  4. #4
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    Can my board support 0.8V only cards is the question
    if i bought one would it work

    According to Intel, my chipset DOES support AGP 3.0 - which must be able to use 0.8V, and can be able to use 1.5V
    :- http://www.intel.com/technology/agp/3_0toverview.htm
    :- http://www.intel.com/design/chipsets...+e7205_wrkstn&
    :- http://www.intel.com/technology/agp/...al/chapt_7.htm

    But according to Asus, it dosent.
    Who to belive?

  5. #5
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    I currently got an ATi Radeon 9700. It is running at AGP 8x.

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    As I already said, all 8x capable gear MUST also cope with the other end being only 4x capable. This specifically includes the difference in signalling voltage.

    In other words, there is no such thing as an 8x-only mainboard or graphics card.

  7. #7
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    Nooooo... can my board handle 0.8V?
    I know it can handle 8x and 1.5v
    But can it handle 0.8V?
    It says it can only do 1.5V in its instruction manual

  8. #8
    Ultimate Member ComPooTer's Avatar
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    yep thats what i figured out on my asus a7n8x deluxe also, for some reason the card wasnt seated properly and the 8x part was hanging out so it was running 4x fine. lol but yeah i did fix it and put it back into place and now im running 8x

  9. #9
    Xtreme Member NDC's Avatar
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    Peter

    Are there two types of 8x AGP cards which could be either AGP 8x and AGP Pro50 8x?

    I asked this because I noticed that AGP Pro50 8x cards are 1.5V vs. AGP 8x cards which are 0.8V.

    Or are they both the same and the difference is that the voltage is on a cycle by cycle case where the voltage signaling is reduced to 0.8V on 1.5V motherboard slots?

    I'm assuming these two are not the same? Perhaps you can enlighten me with and answer...

    Thanks,

    NDC
    Last edited by NDC; 09-28-2003 at 05:27 AM.

  10. #10
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    i have an AGP Pro 8x slot
    Does that mean 1.5v only then?

  11. #11
    Xtreme Member NDC's Avatar
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    I'm not too sure...

    Here is a link you may want to read though regarding 1.5 vs. 0.8... I don't even have an 8x card but I'm really curious...

    http://www.directron.com/15agpguide.html



    and here is another intersting link... Notice they refer to two types of volatges... AGP voltage and Signaling Voltage...


    http://www.cpuplanet.com/features/ar...0231_2117941_2


    According to various links I've read so far, it appears that 8x slots can accept both 4x @ 1.5v or 8x @ 0.8v....

    It only shows damages that can be done if AGP 1x and 2x (3.3V) cards are inserted into 4x and 8x ONLY AGP slots because of the voltage difference. It shows no reference about 0.8v 8x cards damaging 1.5v AGP slots..
    Last edited by NDC; 09-28-2003 at 05:18 AM.

  12. #12
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    "According to various links I've read so far, it appears that 8x slots can accept both 4x @ 1.5v or 8x @ 0.8v.... "
    We have a winner. Thats coorect as Peter was telling you. There is NO 8x only anything. if you have 4x mobo the 8x card will run as 4x. The only diff being pro and the volt diff is included. Meaning if you have a 8x pro agp socket-and a 8x pro card-its o.k. regradless of volts they gave you. Sides a 8x card running at 1.5v is actually 4x which is still within compat of 4x so inside of 8x spec. Phew. ITs all in the 4x/8x/pro sepc as peter said. There actually is a standard for these things.

  13. #13
    Xtreme Member NDC's Avatar
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    That's not the question I'm asking....

    I'm asking how a 1.5V slot can run at 0.8V.

    Also read my previous posts...

  14. #14
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    so can my AGP 8x Pro go at 0.8v?

  15. #15
    Ultimate Member Rugor's Avatar
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    Normally when they say 1.5v only they mean the board does not support 3.3v signalling. If your board supports AGP 8x it will normally use 0.8v signalling in 8x mode.

    However, you don't select the signal voltage directly, that's all done by the chipset without your intervention. So don't worry about it.
    "Dude you're getting a Dell." Obscure curse from the early 21st Century, ascribed to a minor demon-spirit known as "Stephen?" [sp].

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