Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
Paul wrote:
> The GPU chip on a video card can have the same issues as the
> Northbridge on a motherboard. Depending on which company is used
> to fabricate the chips, the operating voltage of the chip may
> be restricted to voltages less than 3.3V. In other words, a video
> card that is 1.5V only, is designed that way because the chip
> would fry if 3.3V was applied. The chip cannot tolerate the
> extra voltage.
Well, the Pinout of the AGP1,2,3 is always the same.
Like CPU´s having a voltage and a core voltage. I am pretty sure that
the core voltage of the Matrox GPU is still the same like the "4X"
Parhelia (on the box is written 8x). That means also the 4x Parhelia is
a 8x!?
I don´t think they will develop a new GPU for the helpless 8x mode.
For example: If the GPU really needs lower voltage and you drive it
with a 3.3V MB, then it will be just regulated down (as it is yet) to
the needed voltage. Thats not modern, thats 50 Years old....
I mean, if the Bord requests 8x (I think via typedt#) the GfxCard will
just work with 0.8V at the BUS but not not the GPU. If 1x is requested
the Board could run with 1.5 and 3.3, and so on.... The GfX cannot fry,
it regulates the incoming Vddq itself, as it needs. This what happens
at the address lines (0.8, 1.5, 3.3) going to the MB and to the VGA is
a other story but does not depend to the source Voltage.
Otherwise it is also possible, that such a solution was very difficult
for Matrox to succed in, so they made a new Board Design which does not
take care about the 3.3V. and designed it to work flawlessly with 8X.
> If I look for a picture of a Parhelia, I see it has slots in
> the edge connector for both 1.5V and 3.3V. This is probably
> the older 4X only version ? I don't think this one would
> run the I/O at 0.8V. It is difficult to know for sure,
> without product documentation.
Yes, thanks.
Well, on the BOX is written 8X!?
>
http://www.muropaketti.com/uutiskuvat/2002/0514parhelia.jpg
>
> Perhaps because a newer version supporting 8X AGP came out,
> they moved to a 1.5V only chip.
Yeah, thats what I meant. But I see this more as a restriction that you
should buy a new MB, too.
>
> This picture from Newegg, shows a card which is 1.5V only:
>
> "matrox PH-A8X256 Parhelia 256MB DDR AGP 4X/8X Video Card"
>
>
http://www.newegg.com/Product/ShowImage.asp?image=14-106-163-08.JPG,14
> -106-163-09.JPG,14-106-163-05.JPG,14-106-163-06.JPG,14-106-163-07.JPG&
> CurImage=14-106-163-08.JPG&Description=matrox%20PH-A8X256%20Parhelia%2
> 0256MB%20DDR%20AGP%204X/8X%20Video%20Card%20-%20Retail
Yes, now I know. Now I see :-( (I tried to put it in my MB :-()
>
> I think you'll have to return it, or find a motherboard that
> supports 1.5V cards.
Sure. No, no new Motherboard.
>
> As for "0.8 volts", be aware that there are two supply voltages
> (3.3V and 1.5V), and there are two keying slots defined for them.
> The 0.8V mode refers to how the AGP bus is terminated. If the
> AGP bus uses series termination, the full amplitude 1.5V signal
> swing happens. If an AGP card uses parallel termination resistors,
> and the source impedance of the signal matches the termination
> resistors used, the signal swing is cut in half. That is where
> "0.8V" comes from. There is no 0.8V power supply on the motherboard
> for that case. In both cases, the I/O pads are powered by
> 1.5V, with no termination resistors, the signal swing is 1.5V,
> and when the termination resistors are switched on, the
> signal swing becomes 0.8V.
>
> If you look at the playtool.com web page, you'll notice in
> the section that addresses practical configurations of AGP,
> that "AGP 3.0 Card" was removed. That card runs the I/O pad
> voltage from 1.5V, but the AGP bus signal swing is 0.8V. The
> implication of such a card, is the parallel termination
> resistors are fixed in place. The cards that exist today,
> seem to have the ability to add or remove the termination
> resistors, and that is why the I/O signals can operate at
> 1.5V (to talk to a 4X only motherboard) if necessary.
Well, maybe therefore they designed a new board.
But you know that a 0.8V MB is just sending 0.8V and a 3.3V is just
having 3.3V. The Card does not take care about. The GPU Voltage is
restricted (I dont know which core Volatges they use) so and so!!
The GxF cannot fry, if 3.3V is assigned, the voltage regulator on the
GfX should know what to do, and so on. Other, if a Board is designed
for 3.3V means not it cannot work with 0.8 ;-), otherwise is not
possible (it would fry).
> This, of course, does not solve your problem. I think you
> have a 3.3V only motherboard ? Shopping for such a
> motherboard requires great care. I hope your retailer
> will offer a refund...
>
> Paul
Sure, the best AGP Slot available today. ;-) O.K. there are faster
(today) one. But I can remember the series of 4X AGP MB, FastWrites,
DDR RAM, AGP2.0 and more. They were all slower. Maybe the today MB are
now without AGP faults. But as I remember, they are still developing
AGP drivers. I have here AGP440.SYS from Microsoft, shipped with
Service Pack 2. Whoooeew. that fast!
Kind Regards,
Daniel Mandic