Graphic Cards Power Rating - I still don't get it?

Discussion in 'Abit' started by Wayne Youngman, Feb 27, 2004.

  1. Hi,

    I'm trying to *fully* understand how this voltage thing works for AGP
    graphics card.

    AGP 1x-2x = 3.3v
    AGP 4x = 1.5v
    AGP8x = 0.8v

    I have yet to see any AGP 8x card that gives *evidence* that its using 0.8v.
    Looking in the BIOS Health-Menu it always shows at least 1.5v (if not 1.6v).
    I have always (well last 5 months since I had a modern system!) left the AGP
    volts at default, but I'm not 100% convinced so far that the (ABIT)
    motherboard knows what to do. I did make a similar post to this in the
    Graphics newsgroups but didn't really get a useful replies.

    Why is it that AGP 8x is *meant* to run on 0.8v? At first I thought maybe
    that it was because they all use slim wafers for the GPU, but I don't know
    if all AGP 8x cards use skinny micron GPU.

    If I get one more answer like "Don't worry about it if everything works ok!"
    I will do my nut :p

    So all you *Voltage* masters, share your knowledge with me, how come I never
    seen a 0.8v setting in BIOS, or is there some kind of automatic switching.
    What happens to the cards voltage when in BIOS you switch from Auto to 4x or
    8x? is this effecting just voltages or?
    Wayne Youngman, Feb 27, 2004
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  2. Wayne Youngman

    Morgan Guest

    Well my Father in Law found that his old ATI 64mb ViVo card would fit his
    newish system (with onboard graphics) due to the lugs on the card so.....

    A little work with his junior hacksaw and it now fits - I kid you not...!!!
    (and seems to work)

    Might be true but I did find this for him to read (which he dismissed)



    Hard drive is noisy no more.....
    Morgan, Feb 27, 2004
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  3. Wayne Youngman

    ICee Guest

    From this page:

    "An 8x device must be 0.8v, a 4x device can be 1.5v or 0.8v, a 2x or 1x
    device can be 3.3v or 1.5v.
    The connectors are keyed so that you can only use compatible equipment,
    up until AGP 3.0 (8x).
    AGP 1.0 and 2.0 devices using a 1.5v key, signal at 1.5v, while AGP 3.0
    devices use the 1.5v key and signal at 0.8v.
    AGP 3.0 devices must be tolerant of 1.5v signalling though, they won't
    necessarily work, but will not be destroyed if inserted into an AGP
    1.0/2.0 slot."
    ICee, Feb 27, 2004
  4. "ICee" wrote

    ok if that's the case, how come the Radeon 9800 and Radeon 9600XT are both
    running at 1.55-1.6v, there are both AGP 8x cards? I am wondering if the
    motherboard is not setting the correct voltage or something?
    Wayne Youngman, Feb 27, 2004
  5. Wayne Youngman

    ICee Guest

    The voltage is set on the card. As the above says, AGP 3.0 cards (like
    the 9800, 9700,9600,9500) must be tolerant of 1.5v signaling.
    ICee, Feb 27, 2004

  6. Hi,
    well you seem to be clear enough about it in your own head :p hehe. The
    word here is *tolerant*. So you saying that it is operating using 1.5v? as
    in AGP 4x spec. Is there such a thing as a card operating on 0.8v, or is it
    a case that the card PCB receives 1.5v and somehow takes just 0.8v from
    Wayne Youngman, Feb 28, 2004
  7. Wayne Youngman

    Asestar Guest

    He means that motherboard sends 1,5V to agp since your 8x card uses 1,5V
    signalling. If you had old agp1x card, mobo would send (and show) 3.3V to
    agp. Even if your card 8x is using 0.8V, mobo is sending agp 1,5 v, out of
    which the gfxboard then uses 0.8V.

    Hope this help..

    PS: It's either that, or your mobo is forcing use of agp4x, and no above.
    Use an utility like aida32 or even catalyst panel to find out what is agp
    x-rating? Is it running 8x? if yes, then above explaination might be correct
    Asestar, Feb 28, 2004

  8. Hi,
    ok that's make it clear!. The thing is I am using AGP 8x cards and whether
    they are set on *Auto* or *8x* in BIOS the card is still receiving 1.6v. So
    I have been manually *reducing* the BIOS setting to 1.5v (lowest), and this
    still reads 1.55v in BIOS health page (better than 1.6v it was on before).
    0.8v/1.5v issue aside, I think the two ABIT motherboards I have been using
    (NF7-S, AN7) are putting out too much voltage. As I said if I leave the AGP
    volts set on *AUTO* the board is deciding that the cards need 1.55v, then
    the boards *overvolt* another 0.05v so I end up with 1.6v, a far cry from
    the 0.8 volts I read about . . . .

    The whole reason I am looking into this is one of my builds (AN7/9600XT)
    will *reboot* after a duration of intense activity, and I was wondering is
    the *AGP-Over-Voltage* could be a possible cause. I heard about setting the
    AGP SPEED to *Auto* in BIOS and 4x in SmartGart to see if this helps. . . .
    Wayne Youngman, Feb 28, 2004
  9. Wayne Youngman

    ICee Guest

    Nothing is being "overvolted". The AGP 3.0 card has a 1.5 volt "key" on
    the card, meaning it will get 1.5 volts from the MB. The card actually
    runs, like any other card, off +5v, +12v for *power*, but the 1.5v and
    ..8v is for *signaling*; Input/Output. Just like CPU's use +12 volts for
    power, but the actual data lines use a small voltage (can't remember
    what it is now). The 1.5v/.8v is the data lines voltage.
    I have the ATI 9500 Pro video card on my NF7-S, and it's running at AGP
    8x (according to SmatGART), settings in the BIOS are Fast Writes ON, AGP
    Auto, AGP voltage, 1.5v. 1.55v is well within tolerance.

    Regarding your problem, set the AGP to 4x, turn fast writes OFF. See if
    this helps the stability problem. I have read that 8x isn't all that
    much faster than 4x, and that if fast write is enabled, it can cause
    problems similar to what you are experiencing.
    ICee, Feb 28, 2004
  10. Wayne Youngman

    Asestar Guest

    To clear it up even further, like Icee said, gfx card uses 1.5V input
    voltage. however data is sent in 0.8V pulses. It's kinda like your power
    supply. It requires 220V to run (100-something for usa, i think) but output
    is 12V, 5V, 3.3V etc..
    Asestar, Feb 28, 2004
  11. Wayne Youngman

    Amir Facade Guest

    OK, but tell me why my 8x ATI 9500np has its own 12v connector direct from
    the PSU?
    I'm so cornfused!!!

    PS: Who's on first?
    Amir Facade, Feb 29, 2004
  12. Wayne Youngman

    Frank Hagan Guest

    No, Who's on second ;-)

    Frank Hagan, Feb 29, 2004
  13. Because it needs more 12 volt power than is allowed, by the AGP 3.0 spec,
    to go through the motherboard connector.
    David Maynard, Feb 29, 2004
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