Not including the 6800GTO, does there exist an Nvidia 6800-based PCI
Express / SLI video card that supports dual-link DVI signalling
required to drive the Apple 30" Cinema HD Display at its optimal
resolution of 2560x1600?

The 6800GTO is not applicable because while it can drive the display
at its optimal resolution of 2560x1600, it is neither SLI certified
nor supported by vendors in an SLI configuration.

---

Clarification of Question by kevinying-ga on 25 Feb 2005 18:48 PST

Examples of unsatisfactory answers:
* Nvidia Quadro FX series video cards (based on the 6800 but not the
same as a 6800 video card)
* Asus V9999 Gamers Edition video card (AGP, neither SLI nor PCI Express)
* Nvidia 6800GTO PCI Express video card (not SLI certified)

---

Request for Question Clarification by denco-ga on 25 Feb 2005 20:51 PST

Howdy kevinying-ga,

Would a card with the following specifications meet your needs?  Thanks!

- NVIDIA SLI Multi-GPU Ready
- 16x PCI Express
- NVIDIA GeForce 6800 GT graphics controller
- Dual DVI-Out digital output

Looking Forward, denco-ga - Google Answers Researcher

---

Clarification of Question by kevinying-ga on 25 Feb 2005 23:00 PST

"Dual DVI-Out digital output" is the contentious term that many
vendors are using but is not accurately describing the feature.  This
refers to dual DVI output which is not the same as dual-link DVI
signaling, which can be support on one or both DVI digital outputs of
a video card.

Here's a good explanation from Tom's Hardware Guide:
http://graphics.tomshardware.com/graphic/20041129/tft_connection-06.html

---

Request for Question Clarification by denco-ga on 26 Feb 2005 13:12 PST

Much thanks for the clarification, kevinying-ga.  That helps quite a bit.

Will keep on looking, denco-ga - Google Answers Researcher

Might try this.  While i don't know what you want to use it for, if
you check out the 3dlabs website, (a divisioin of Creative) you can
find their professional video cards.  Not SLi, but this one
http://www.3dlabs.com/products/product.asp?prod=293, the realizm 800,
has dual link out and a nice hefty 640MB of ram.

I have been chasing answers to a very similar question and asked the
following question of Gigabyte customer support:

----------
Question - 182910, Sent : 2005/3/3 12:50

"I need to know whether any of your VGA models support "dual-link" DVI
output. Unfortunately YOU DO NOT PROVIDE THIS INFORMATION IN YOUR
SPECIFICATIONS, and I don't know where to find out without asking
here!

I wish to drive an Apple 30" Cinema LCD display at its native
resolution of 2560x1600 at 60Hz refresh and this is only possible with
a dual-link DVI port. Please note I am NOT asking about dual DVI
connectors to drive two screens, I am asking about a SINGLE DVI socket
with "dual-link" capability to drive a single screen with higher than
normal resolution. Are any of your latest Graphics Accelerator boards
capable of this?

I have downloaded some of your manuals and I notice that your X850
model allows 2048x1536 at 66Hz (multiplied gives 208MHz min pixel
clock rate), and your 6800Ultra and 3D1 models allow 2048x1536 at 85Hz
(267MHz min pixel clock rate). The DVI 1.0 specification says "Any
pixel format and blanking interval requiring more than a 165MHz-clock
frequency must be supported using two T.M.D.S. links." - ie a
"dual-link" DVI port. So one would think that all of these DVI ports
should be dual-link capable. However I am told by those who should
know that typically all the currently available PC compatible (ie
non-Apple) 3D grapics boards only support "single-link" DVI ports
(although they may have two of them). Also your manuals suggest
strongly (see for example the diagram on page 4 of
manual_nx68u256db_e.pdf) that the ports are single-link since both DVI
sockets are drawn with the middle six pins (the dual-link pins)
blanked off!"
----------

For which I received the following reply (in part and together with an
apology for taking a long time to answer):

----------
"Thank you for your kindly mail and supporting GIGABYTE.
About the issue you mentioned in your earlier mail, please refer to
the GV-NX68U256D-B, GV-NX68T256D-B and GV-N68U256D. They supports
Dual-Link DVI output."
----------

You will note that the two NX boards (PCIe) listed are SLI capable and
should be an answer to your question.  However I have no confidence in
this reply whatsoever.  It seems to me the guy has not bothered to
read my question properly, but simply glanced through their products
and naively picked out the units obviously fitted with two DVI ports. 
A follow up question is probably in order but I am tired of banging my
head against a brick wall!

I asked similar questions of ATI cusomer support but after an initial
blunt and unsatisfactory reply, they ceased their human support
service and replaced it with an automated system that simply responds
with some useless FAQ reply.  Here  are the questions I tried to put
to ATI:

----------
"Dual-link DVI port on *PC* graphics cards?

I wish to drive a 30-inch Apple Cinema Display using one of your PC
(ie not Mac) cards.  The critical item missing from all your PC card
specifications is whether the card supports a dual-link DVI
connection.  This information is present in your Mac card
specifications "(one Dual Link DVI and one ADC port)" but is missing
from your PC card specifications where it typically only says
"Integrated 165 MHz TMDS transmitter (DVI 1.0 / HDMI compliant...".

I noticed that your X800 specifications state that the card can do a
resolution of 2048x1536 at 85Hz.  These numbers multiply out to give a
pixel clock frequency of 267MHz minimum.  The DVI 1.0 specification
says "Any pixel format and blanking interval requiring more than a
165MHz-clock frequency must be supported using two T.M.D.S. links." -
ie a "dual-link" DVI port.  So if the DVI port is capable of
2048x1536@85Hz, and is DVI 1.0 compliant, as your specification
states, then it MUST have a "dual-link" DVI port!

However when I asked the question of your customer care I was told
(TicketGUID:{0F39D7D4-313D-4C2B-A325-60812809EC61} that "The Radeon
X800XT PCie card DOES NOT support Dual Link DVI"... How is this
possible?

If true and the X800XT does not support Dual Link DVI, are there any
other PC (non-Mac) graphics cards that can support a "dual link" DVI
connection ? (which should then be capable of driving the Apple 30"
LCD display)."
----------

I am still researching this question with much frustration.  I fear
the answer is not to be found on the web, nor even from sales reps
unfortunately.  So I look forward to any answers that might be posted
here!

From the ppl who seem to know the difference between dual DVI output
and dual-link DVI signaling, here's what I've gotten from tech support
vendors:

XFX - no support
eVGA - no support
MSI - only supported in latest PCI Express 6800 Ultra (no independent
verification yet)
ATI - no support in Radeon cards; use FireGL only
Nvidia - no support in 6800 cards for PC; use Quadro only

The rumor is that the Nvidia 6800 Ultra 512MB will support it.  No
independent verification on this either.

As everyone is beginning to experience, you cannot even rely upon tech
support for the answers they provide since they might just check their
own erroneous web page.  We can only rely upon their engineeers (as I
was able to contact @ eVGA) or independent PC hardware reviewers that
actually test against sample hardware.

Thanks for that information - it must have taken you a while to collect!

What I cannot understand - and you will see I have attempted to find
out above - is how it is possible to achieve the resolutions and frame
rates that they claim (ie 2048x1536 at 85Hz) without using dual-link
DVI!  They typically say they are compliant with DVI 1.0 but if you
read the spec it states that this sort of pixel rate demands the use
of a dual-link connection.

The only answer I could guess at was that the VGA connection managed
the high frame rates while the DVI single-link connection
(deceivingly) did not.  But when you have no VGA connection but just
two DVI ports, what then?  Do you need to connect both DVI ports to a
single monitor to get the frame rates they specify?  Surely not!

It seems that it's more than a rumour that the 512Mb version of the
6800 Ultra will support the Apple 30" - nVidia spell it out in black &
white in their ForceWare Graphics Drivers Release 70 Notes:

http://download.nvidia.com/Windows/71.84/NVWinRel70Notes_7184.pdf

From page 56 (page 50 in the document):
------------------------
Table A.1 Modes Supported for High Resolution Displays
Display                  Maximum        Resolution Hardware Requirements
IBM T221                 3840x2400 @    ? All High-end Quadro FX (see list of
(Dual Link DVI)          48Hz             products in ?Quadro FX Family of
                                          High End GPUs? on page 59.)

Apple 30? Cinema HD      2560x1600 @    ? All High-end Quadro FX (see list of
Display (Dual link DVI)  60Hz             products in ?Quadro FX Family of
                                          High End GPUs? on page 59.)
                                        ? GeForce 6800 with 512 MB
------------------------
It couldn't be much more specific than that, I'd say. And the 6800
Ultra should definitely be SLI, though I'm not sure about SLI support
in that particular resolution (native 2560 x 1600).

From the press release, it seems these cards will be available sometime in April:

http://www.nvidia.com/object/IO_19395.html

I've had an Apple 30" myself for about a month now, without being able
to drive it at the native resolution. You could say I've been 'eagerly
anticipating' this information...

Hi flotsam, soekev here ;)

The news about the 512MB 6800 is certainly what we 30" owners have
been waiting for.  However, I've seen pictures of the 512MB card and
haven't seen the TMDS transmitter on the back of the card.  Hopefully
it's elsewhere.

I did receive a 6800GTO today and there are 2 external TMDS
transmitters on the card: 1 on front, and the 2nd on the back.  The
location of the 1st is on the flipside of the PCB where the rear is
soldered on.

Hopefully a vendor will receive a batch of the 512MB cards and can
verify for us all.

I hassled Gigabyte again to see if they were sure about their DVI
boards supporting dual-link.  Here is the question I asked :-

----------
...However I fear that you have not read or understood my question
properly and may have simply picked out units fitted with two DVI
ports. If so then this is NOT THE ANSWER I NEED. I am quite capable of
looking at your specifications and pictures to find out which models
are fitted with dual DVI ports.

Rather I need to know if either or both of the DVI ports have
"DUAL-LINK" capability. A DVI port with dual-link capability has TWO
sets of wires for each colour (Red,Green,Blue) in the ONE DVI socket,
instead of just one set for each colour. If you don't know about
dual-link DVI please pass the question to someone who does. If you do
know about dual-link DVI and have answered the question correctly,
then please accept my humble apology.

If you look at the diagram on page 4 of the manual for the
GV-NX68U256D-B (manual_nx68u256db_e.pdf) you will see that the middle
six pins are shown blanked off. These middle pins are the dual-link
pins and are needed for driving high resolution displays at high
refresh rates. Although they are obviously not blanked off in the
photograph of the GV-NX68U256D-B, this does not mean that they are
connected and active. I NEED TO KNOW IF THESE PINS ARE CONNECTED AND
ACTIVE in any of your models. Whether the model is fitted with only
one DVI socket or fitted with two DVI sockets does not matter.

Alternatively you could simply indicate whether any of your PC based
video boards are capable of driving the 30" Apple LCD display at its
native resolution of 2560x1600 and 60Hz refresh rate?
----------

And here is the answer they sent :-

----------
We are sorry that the information was not clear enough. As to the
problem you mentioned, from the information provided by our engineer,
this graphics supports Dual-Link DVI. However, in order to provide you
a much certain answer on whether it supports 30" Apple LCD display at
its native resolution of 2560x1600 and 60Hz refresh rate, our engineer
will double check with the chipset vender, nVidia about this issue.
Sorry for the inconvenience that has encountered.
----------

So according to their engineer at least the GV-NX68U256D-B and most
likely the other two they listed in their first answer do in fact
support dual-link DVI!

I don't know whether they will supply a second answer (ie about
driving the 30" LCD) to the one question, but I guess I will keep a
lookout in case they do.

Hi all. Bit of a waffle follows, I'm afraid:

Firstly, ARGH. :-)

I've been trying to find answers to much the same question - except that
I have an IBM T221, not a 30" Apple. I'm awaiting a 6800GTo (I had one;
it was definitely dual link, although the other head used the internal
TMDS transmitter and was a bit borderline; I sent it back when I found
it wouldn't SLi; the consumer GTs which MSI claimed were dual link
*weren't* - a gap surrounded by solder pads where at least the SiI1178
on the back should have been; the replacement GTo I've just received was
dead...) but have been trying to find a dual link board of any kind for some
time. If the Gigabyte boards turn up just in time to make my GTo scrap
metal, my teeth will grind.

To add some data points, since I seem to have been asking the same
kind of people the same kind of question...

Inno3D: Boards are definitely not dual link (but they thought they were,
for a while).

XFX: Boards are not dual link, and they seem to think the Apple DDL card
is a PC card (at least according to the people I spoke to last year, it
won't work in a PC).

MSI: I confirm that the GTo *is* dual link (and looks almost identical
to a Quadro FX3400). Having got an answer handed down to me from someone I
gather is their product designer, they seem to think the 6800 is dual-link
capable without external TMDS transmitters, so they think some of their other
boards are dual link too. I beg to differ.

nVidia: Claim it's entirely up to their board engineers. I've pointed out
that at least two consumer cards can run the Apple 30", but they've not
updated their FAQ (and automatically pointed me back at the entry which
I was telling them was wrong...) I wouldn't mind it being "up to the
board manufacturers" if there was any indication that the board manufacturers
knew what they were doing (and if nVidia weren't the people who'd know about
the drivers).

I've not had much luck getting anything back from other board manufacturers.

I'm sticking with nVidia because of the Linux driver quality (and I want
SLi and PS3.0, although these won't allegedly be nVidia-specific as of R520).
My sticking point at the moment is whether I spend a fortune on 512Mb Ultras
or whether I wait for G70 to turn up. I'm not sure what the list price on
the Ultras will be, but FireGL and RealiZm 200 cards won't be far above...

To get a straight answer out of Gigabyte, it might be worth asking them
specifically whether the new boards have SiI1178s (or equivalent) on them,
and, if so, how many. This would hopefully answer the question without
giving them the chance to get confused. It wouldn't surprise me too much
if the 512Mb boards *are* dual link, because Gigabyte could just copy the
Quadro FX4400 design (which is likely to be almost identical). Seeing
whether these chips are there should be fairly easy for someone non-technical
to do, and doesn't rely on a board designer (given that many boards are
clones of the nVidia reference) to be helpful - chances are there are wires
going to the DVI connector pins even if they're not linked to anything
on the board.

I'd be interested to know, if anyone can find out:
1) Whether the Gigabyte boards have two dual link heads (like the 4400) or
   just one (or *even* one!);
2) Why the T221 isn't listed as supported (it needs a dual link + a single
   link; it's a bit dicky with an internal TMDS transmitter, so it may be
   that the Gigabyte board only has one external pair of 1178s);
3) Whether the 512Mb is actually available to all applications (on AGP
   boards there are issues with making >256Mb available to DirectX because
   of the AGP aperture size; PCI-e may differ; cards like my VP990 can use
   the extra for OpenGL) - otherwise it's (arguably) a bit of a waste of
   money for consumer apps, unless you *really* like Doom 3.

Incidentally, I'd not take the 2048x1536 specifications as any indication
of DVI capability - this figure almost definitely refers to the maximum
resolution the RAMDAC supports from the analogue output, and many single
link DVI cards claim the same. Many (but not all) such cards have "1600x1200
maximum digital resolution" in the small print.

Well done for your hard work, everyone. I'll keep an eye here for news,
and obviously post anything I uncover.

As I know, not all nVIDIA VGA cards come with dual DVI connectors will
support DUAL-LINK DVI feature. Only high-end wrokstation level GPU,
Quadro FX or Quadro 4 with dual DVI connectors supports DUAL-LINK DVI
feature.

sammyho-ga: That's nVidia's official line, but it's clearly not actually
the case. Ignoring at least three Apple cards which support dual link,
the V9999GE and 6800GTo *are* both dual link cards, and nVidia's drivers
support them. The reference boards for the 6800 series were also, I
understand, dual-link capable (although obviously you can't buy them).

Since the board manufacturers are clearly confused about this, it would
really be helpful if nVidia would try to straighten out the situation -
but they may be determined to get Quadro sales out of those of us in need
of $30 of TMDS transmitter (I'm not able to pay Quadro money for sub-
consumer card performance, since I don't need the Quadro drivers). Maybe
Silicon Image would say something?

Matrox just launch a card for getting the Apple 30" to run on a PC..

http://www.matrox.com/mga/workstation/digital_design/news/press_rel/2005/parhelia_dl256.cfm

Here are the first announced PCI_E SLI cards that support Dual Link
DVI and the 30" Apple Cinema Display at full resolution:
http://www.evga.com/articles/public.asp?AID=240

Unfortunately, the Parhelia is not up to snuff with respect to game
performance, but not everyone needs gaming performance, so it's good
to know.

Great find on the eVGA press release.  Nice to see some official
product announcements that confirm the dual-link DVI support.  I
notice that there's a VGA cable coming out of the eVGA 512MB SLI
config, though... it could be that there haven't been any official
drivers released that work seamlessly w/ DVI.  I heard that we'll have
to wait for 78.20 for widescreen DVI to work w/ SLI w/o problems.

Here's some more confusion within MSI US about the Apple 30" Cinema HD
Display; it seems that their tech support is confused about the Apple
hardware and misinterprets my query:

First question was submitted via their online form and received the
following reply:
From: MSI Technical Support Team USA <usersupport2@msicomputer.com>
Since MSI does not state any support for MAC, only PC for all video cards.
---> an obvious misinterpretation, perhaps they thought I was asking
to install the 6800 into a Mac?

When I kindly informed them that the Apple 30" would work on PC
hardware as well, they replied:
"Since we do not provide any MAC driver for the video
cards, how can it work?
Since the DVI out the video card can only support the DVI-I spec, please do
check on the monitor spec for this input too.
No, only Quadro or Apple 6800 version support Dual link."

And last, I asked simply: "OK, please answer this simple question:
Does the NX6800V-T2D256E support dual-link DVI signaling on 1 or more of 
its DVI outputs?"

And their reply: "No, the MSI NX6800U-T2D256E does not support
dual-link DVI signaling."

Yet MSI TW has confirmed that the card works @ 2560x1600.

I had the same problem and am presently on a Cinema HD30 apple display
with a Apple Cinema HD 23 display (dual display system) using a pc and
an ATI FireGL V7100 video card.  It works GREAT! Hope this helps!

It would be nice to find out if anyone knows of where you can get a
set of pc drivers for the apple NVIDIA GeFource 6800 Ultra DDL.  It
cost MUCH less and should work fine on a pc.  I called apple and got
the run around, called NVIDIA and also got the run-around.