AGP 2.0

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Daniel Mandic

Hello!



Is a AGP 2.0 (Cards with 3.3v and 1.5V inserts) Gfx Card at 1x or 2x,
working with 3.3V?
I know that 4x needs 1.5V.



Best Regards,

Daniel Mandic
 
Daniel Mandic said:
Hello!



Is a AGP 2.0 (Cards with 3.3v and 1.5V inserts) Gfx Card at 1x or 2x,
working with 3.3V?
I know that 4x needs 1.5V.



Best Regards,

Daniel Mandic
Click to expand...

Maybe this link will help. There are plenty of tables here,
and you should read the whole page to understand the summary:

http://www.playtool.com/pages/agpcompat/agp.html

If a card can operate at the lower voltage (like 1.5V), it
does all of its signalling 1x, 2x, 4x at that voltage.
It doesn't switch to 3.3V to do 1x, for example. If
it did switch, the 3.3V would burn out a modern 1.5V-only
Northbridge AGP interface.

Paul
 
Hi Paul!



Well, I have found this link, too. Very good link!!
Thanks.


I have ordered a Matrox Parhelia, and prompt they sent the 1.5V Version.
I don´t know why there is even a 1.5V only Parhelia??? Sure, they need
so sell some "modern" MB´s, too :-)

The Original Parhelia can do all Voltages, even 0.8 ... such things
don´t depend to the MB.
****ing PC Business.




Best Regards,

Daniel Mandic
 
Daniel Mandic said:
Hi Paul!

Well, I have found this link, too. Very good link!!
Thanks.

I have ordered a Matrox Parhelia, and prompt they sent the 1.5V Version.
I don´t know why there is even a 1.5V only Parhelia??? Sure, they need
so sell some "modern" MB´s, too :-)

The Original Parhelia can do all Voltages, even 0.8 ... such things
don´t depend to the MB.
****ing PC Business.

Best Regards,

Daniel Mandic
Click to expand...

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.

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.

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.

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/ShowI...helia 256MB DDR AGP 4X/8X Video Card - Retail

I think you'll have to return it, or find a motherboard that
supports 1.5V cards.

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.

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
 
Paul said:
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.
Click to expand...

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.
Click to expand...

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.
Click to expand...

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
Click to expand...

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.
Click to expand...

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.
Click to expand...
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
Click to expand...

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
 
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).
Click to expand...
Kind Regards,

Daniel Mandic
Click to expand...

There was a short interval during which the standard for keying
was ignored by a couple of video card manufacturers. These
cards had the key that said the card would work at 1.5V, but
the card was in actual fact, a 3.3V only card. These cards
burned the 1.5V only motherboards they were plugged into. Asus
"fought back" by adding the AGP_WARN circuit to motherboards,
for about a year or more after the first failures. AGP_WARN
has been removed from recent AGP motherboards, presumably because
nobody wants to use an SIS305 on a modern board.

With the exception of that incident, keying on AGP slots works,
and prevents voltage issues. If you buy a new video card, you
don't have to worry about burning something. As long as the
video card fits, it won't burn anything.

With the AGP 3.0 standard, there are now three status signals
on the AGP connector. They were not always there, and were
added after the initial standard for AGP was released.

There are two keying slots. A 1.5V key and a 3.3V key. The
TYPEDET# signal, is sent by the video card, to the AGP slot.
If you use a universal video card, which has two keys, the
video card can have TYPEDET# grounded, and that is the way
the video card asks the motherboard VDDQ regulator to
run at 1.5V. That is the "tie breaker". The TYPEDET# signal
probably wasn't in the first spec, so on an older video
card, that signal would be floating. That indicates a
request for 3.3V.

The motherboard is responsible for regulating VDDQ. The video
card TYPEDET# signal indicates the video card's preference,
and if the motherboard is universal, it will look at the
signal. A 1.5V only motherboard, of course, will ignore
TYPEDET#, and it will only deliver 1.5V to the video card
(and the Northbridge AGP interface power).

Since the motherboard provides the voltage, the video card
is helpless to do anything. The video card cannot regulate
down the voltage, because the Northbridge AGP interface
and the video card AGP interface have to run at the exact
same voltage. The motherboard controls the voltage sent to
both devices, so the video card is a "slave" to the
motherboard.

Details about the other two status signals can be found in
the AGP 3.0 spec, so I won't repeat them.

Paul
 
Paul said:
Details about the other two status signals can be found in
the AGP 3.0 spec, so I won't repeat them.

Paul
Click to expand...

Yes, Yes.

As I said. You cannot burn a Card capabale of 3.3 with 0.8 or 1.5V.
Otherwise it does not fit into the Slot. Thats all :-)


Sure, the current on the BUS and Northbridge have to be the same.
But it is possible that the GPU have an other Voltage, that I meant.

The GPU is not directly connected to the MB Chipset, it is buffered,
like it was always before (ISA, VESA, PCI).
The lower voltages of 0.8 and 1.5 are just made for a stable 8x and 4x,
which don´t work with 3.3V. But I don´t care about 8x and 4x as this
speeds nothing up. More Important is a good stable AGP driver.


I saw on the link that you gave to me, that there are two 3.0 AGP
Standards today.
One with all voltages and one with only 1.5 and 0.8. I cannot
understand why???
As I understood, every Universal 3.0 AGP GfX will fit and work in my
(AGP 1.0) MB and in every other. But not the Universal 1.5V 3.0 AGP -
for what is this Standard good?



Best Regards,

Daniel Mandic
 
Daniel Mandic said:
Yes, Yes.

As I said. You cannot burn a Card capabale of 3.3 with 0.8 or 1.5V.
Otherwise it does not fit into the Slot. Thats all :-)


Sure, the current on the BUS and Northbridge have to be the same.
But it is possible that the GPU have an other Voltage, that I meant.

The GPU is not directly connected to the MB Chipset, it is buffered,
like it was always before (ISA, VESA, PCI).
The lower voltages of 0.8 and 1.5 are just made for a stable 8x and 4x,
which don´t work with 3.3V. But I don´t care about 8x and 4x as this
speeds nothing up. More Important is a good stable AGP driver.
Click to expand...

Ah, but it is directly connected.

GPU_memory CPU
| AGP bus |
VGA--GPU-------------------------Northbridge---Motherboard_memory
(common I/O voltage) |
southbridge
|
PCI slots

The AGP bus is a point-to-point bus, with an agent at each end.
They share the same VDDQ. VDDQ is provided by the motherboard
regulator.
I saw on the link that you gave to me, that there are two 3.0 AGP
Standards today.
One with all voltages and one with only 1.5 and 0.8. I cannot
understand why???
As I understood, every Universal 3.0 AGP GfX will fit and work in my
(AGP 1.0) MB and in every other. But not the Universal 1.5V 3.0 AGP -
for what is this Standard good?



Best Regards,

Daniel Mandic
Click to expand...

The difference between the two AGP 3.0 options, is due to the
technology options available to the video card makers. Some
chip fabs can support 3.3V and 1.5V VDDQ, others will only work
at 1.5V VDDQ. It is the same with Northbridge chips. For a
while now, Northbridge chips have been restricted to 1.5V VDDQ for
AGP. In fact, the Northbridge chips were the first devices to
"change the rules", by operating at only 1.5V. Video card makers
have worked much harder, to try to maintain backward compatibility.
But the thing is, technology marches on, leaving behind it,
all sorts of perfectly good legacy things.

The same kinds of issues happen with FPGA and CPLD programmable
chips technologies. Many of them no longer can handle all the
voltages that the PCI bus support (like 5V I/O), meaning there
are fewer and fewer ways to make fully backward compatible PCI
cards easily.

These pages are the last remaining info on ATI cards. These pages
have been removed from the ATI site, or at least I can no longer find
them.

http://web.archive.org/web/20041103055247/http://www.ati.com/support/agpchart/agp.html
http://web.archive.org/web/20041014040007/http://mirror.ati.com/support/faq/agpchart.html

You can see in the first chart, several of the highest performance
ATI cards no longer handle 3.3V, so Matrox is not the only company
doing this.

Paul
 
Paul said:
Ah, but it is directly connected.

GPU_memory CPU
| AGP bus |
VGA--GPU-------------------------Northbridge---Motherboard_memory
(common I/O voltage) |
southbridge
|
PCI slots

The AGP bus is a point-to-point bus, with an agent at each end.
They share the same VDDQ. VDDQ is provided by the motherboard
regulator.
Click to expand...

Whow, Agents, hm?
Sorry I cannot follow your Politic.

Ah, AGP 2.0 and 3.0 also have a 3.3V VCC. What do you say now?
The difference between the two AGP 3.0 options, is due to the
technology options available to the video card makers. Some
chip fabs can support 3.3V and 1.5V VDDQ, others will only work
at 1.5V VDDQ. It is the same with Northbridge chips. For a
while now, Northbridge chips have been restricted to 1.5V VDDQ for
AGP. In fact, the Northbridge chips were the first devices to
"change the rules", by operating at only 1.5V. Video card makers
have worked much harder, to try to maintain backward compatibility.
Click to expand...

So far I know, the only need of lower voltage is for 4x and 8x. This
have nothing to do with the GPU, thats the current between the GPU and
Northbridge. And a 3.3V GPU should work at 1.5V as well.

Maybe you can follow me: Once again, The Parhelia Univ. 3.0 AGP is
working in all MB with an AGP Slot. 1x, 2x, 4x and 8x. So it is written
on the box. In big letters "8X"
Yes, there is a 1.5V only version, but no need for it.

AGP is still the same, the backward compatibilty you mean is about 3-5%
performance decrease :-), compared to 4x and 8x.

But the thing is, technology marches on, leaving behind it,
all sorts of perfectly good legacy things.
Click to expand...

You can still buy brand new ISA VGA Cards with 4 and 8MB.
I think you mean something other with marche. I don´t like marches.
The same kinds of issues happen with FPGA and CPLD programmable
chips technologies. Many of them no longer can handle all the
voltages that the PCI bus support (like 5V I/O), meaning there
are fewer and fewer ways to make fully backward compatible PCI
cards easily.

These pages are the last remaining info on ATI cards. These pages
have been removed from the ATI site, or at least I can no longer find
them.

http://web.archive.org/web/20041103055247/http://www.ati.com/support/a
gpchart/agp.html
http://web.archive.org/web/20041014040007/http://mirror.ati.com/suppor
t/faq/agpchart.html

You can see in the first chart, several of the highest performance
ATI cards no longer handle 3.3V, so Matrox is not the only company
doing this.

Paul
Click to expand...

Well, they want to sell new hardware, otherwise they would starve :-)

But you are argumenting pretty hard :-). That´s really funny.




Kind Regards,

Daniel Mandic
 
Hi!

----------------------------------------------
Briefly, the complete listing of pinout changes is:


Signal Pin# Type Description
AGP_Vrefcg B66 static mainboard to graphics card reference voltage
AGP_Vrefgc A66 static graphics card to mainboard reference voltage
GC_DET# A3 static forces AGP 3.0 mode on graphics card
MB_DET# A11 static forces AGP 3.0 mode on mainboard
DBI_HI A12 source synchronous DBI upper block (AD[31:16])
DBI_LO B14 source synchronous DBI lower block (AD[15:00])
---------------------------------------------

This I have found on the Internet. But no mention about a changing of
the VCC.
VCC is the term for Source Voltage.


I also tried to find pinouts for the AGP 3.0. No Chance, Intel removed
the 3.0 Page totally. I just find Pinouts for 1.0 and 2.0. But nothing
changed with AGP except the 4x and 8x mode which cannot work with
3.3Vddq, sure.

I could tell you how this 1x 2x 4x is working but it will be so long
....... In short: complicated thing, not really reliable (2x is already
unstable) and no performance increase at all.



Best Regards,

Daniel Mandic
 
Daniel said:
Whow, Agents, hm?
Sorry I cannot follow your Politic.
Click to expand...

The point is that both the graphics card and the northbridge have to
support the I/O voltage (VDDQ) to be used. More supported voltages means
more effort - it's always a tradeoff between compatibility and cost.
This doesn't even have a lot to do with engineering, it's plain common
sense. (Also expressed as TANSTAAFL.) Additional factors like the
progress in semiconductor technology also play a role.
Ah, AGP 2.0 and 3.0 also have a 3.3V VCC. What do you say now?
Click to expand...

That is specified for backwards compatibility. There are some AGP 8X
cards that work just fine in old 3.3V-only boards. However, you can also
find AGP 1X - 8X cards that will be little fun in 3.3V-only boards, with
frequently unstable operation and hardly any AGP o/c being possible.
Think ATI R300 (Radeon 9500/9700). It's not too amazing that newer
incarnations of the chip only support 1.5 and 0.8 V I/O. (Which is too
bad, I sure would have liked to use a 9600.) You seem to think that
there's an awful lot of additional hardware on the cards and mo/bos to
enable a broad range of voltages, but this is not the case. That's all
highly integrated stuff, and in fact you want as little additional parts
as possible in the signal path for best signal quality. Back in the day
with the first attempts to measure AGP power consumption, AGP
interposers were tried - but those would even make things unstable in
AGP 1X sometimes.
Maybe you can follow me: Once again, The Parhelia Univ. 3.0 AGP is
working in all MB with an AGP Slot. 1x, 2x, 4x and 8x. So it is written
on the box. In big letters "8X"
Yes, there is a 1.5V only version, but no need for it.
Click to expand...

So if you got the newer version that's useless for you, you may want to
ask Matrox whether there's been a part number change and what the P/N of
the old version is so you can search for that one. In the meantime you
can return the card that doesn't fit. Starting endless discussions here
doesn't help in the very least.
You can still buy brand new ISA VGA Cards with 4 and 8MB.
Click to expand...

See? No 3D acceleration, no 64 megs of memory or more. You can also
still buy PCI graphics cards with today's low-end chips, but these don't
work in old boards with 5V-only PCI either.

BTW, if you want to have real "conservative" hardware, get into sound
cards. ;) There still are quite a number of 5V-only cards there, even
relatively new ones (e.g. Hercules Fortissimo IV, Audiotrak Prodigy
7.1LT; Creative, M-Audio and RME have, however, been making
3.3V-compatible cards for a while).

Stephan
 
Stephan said:
meantime you can return the card that doesn't fit. Starting endless
discussions here doesn't help in the very least.
Yes.

BTW, if you want to have real "conservative" hardware, get into sound
cards. ;) There still are quite a number of 5V-only cards there, even
relatively new ones (e.g. Hercules Fortissimo IV, Audiotrak Prodigy
7.1LT; Creative, M-Audio and RME have, however, been making
3.3V-compatible cards for a while).
Click to expand...

Hmm, I cannot follow you.
Is a 5V a ISA and the 3.3V a PCI?
Stephan
Click to expand...


Best Regards,

Daniel Mandic
 
Paul said:
Ah, but it is directly connected.

GPU_memory CPU
| AGP bus |
VGA--GPU-------------------------Northbridge---Motherboard_memory
(common I/O voltage) |
southbridge
|
PCI slots


Paul
Click to expand...



GeForce 6800



Best Regards,

Daniel Mandic
 
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