Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
In article
<yP1Dc.515776$Ar.35920@twister01.bloor.is.net.cable.rogers.com>,
"Stringfelowhaulkie" <string@felow.haulkie> wrote:
> I have a ASUS A7V333 rev 1.02 BIOS 1016. And I want to put in a ASUS Radeon
> 9600XT DVT 128mb AGP card. The box says "Bus Standard AGP 8X/4X/2X"
>
>
> How do I put the voltage to 3.3 for the AGP slot? ASUS Probe 2 says "Slot
> Characteristics: Provides 3.3V"
> ASUS display cards consume more electrical power so that your motherboard
> must be able to provide enough electrical current in 3.3V power to maintain
> its normal operation.
>
> On the MB jumper JP1&JP2 are in-behind the AGP slot which I haven't been
> able to find what they do. There not documented! I think there to set the
> AGP slot voltage.
> Does anyone know if I'm correct? Is thier any documentation on these
> jumpers and where?
>
> Thanks everyone!
The voltage is determined automatically. If the motherboard only had
3.3V I/O, for example, it would have a 3.3V plastic key in the AGP
slot, and only a universal or a 3.3V only card could fit in the slot.
If the motherboard slot is universal, having neither the 1.5 or 3.3V
key, then the motherboard can operate at 1.5V or 3.3V (that is what is
show in the manual - the picture of your motherboard shows a universal
slot). In a situation where the video card is universal (has two slots
cut in it) and also the motherboard is universal (has no plastic keys),
pin A2 (TYPEDET#) is sent by the video card, to the motherboard,
indicating the card prefers 1.5V. It does this by grounding the pin A2.
I believe your new video card will request 1.5V from the motherboard.
Looking at this ATI webpage, your hardware will be either case F or
case I at the bottom of this page:
http://mirror.ati.com/support/faq/agpchart.html
As for the third voltage level, 0.8V, there is no such supply pin. To
make 0.8V I/O, the drivers are still running from 1.5V. The bus has a
parallel termination on it, and by voltage divider action between the
source resistance and the termination resistor, a half amplitude signal
results. One half of 1.5V is roughly 0.8V.
(Pg. 65 shows 1.5V drivers making 0.8V signals)
http://developer.intel.com/technology/agp/downloads/agp30_final_10.pdf
Just plug it in and let the designers worry about it.
There were video cards you had to be careful with, because they
weren't keyed properly. These are termed "illegal" video cards, and
they would be several years old. Most modern Asus motherboards have
an "AGP_warn" circuit, that detects the illegal video cards, and
prevents the motherboard from powering up, if it finds one. So,
again, illegal video card plus modern motherboard, is covered by
design.
The only really bad combination left, is some of the first 1.5V
only Northbridge chips were placed on motherboards without the
"AGP_Warn" circuit. A number of these motherboards were destroyed,
until people figured out that there was such a thing as an "illegal"
video card. For example, the motherboard I bought, the P4B (which takes
a P4 processor and SDRAM), was suspectable to damage by illegal
video cards, up until revision 1.05 of the motherboard. When I bought
my board, I was very careful to verify I was getting a 1.05
motherboard, with one of the first "AGP_warn" implementations on
it.
With the more modern hardware you own, just plug it in and
enjoy it
Paul
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