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TMDS transmitter chips on 7800 GTX and X850 XT dual DVI cards

E

Ender17

Senior member
Anyone have info on what TMDS transmitter chips are being used on the 7800 GTX cards?

I'd particularly like to know if both DVI ports are integrated by nVidia or if the second one is an add on from Silicon Image or another third party.

Also, on the dual DVI X850 XT cards, does anyone know what chip is being used for the second one?
I'm assuming it's an add-on since all the BBA cards only have one DVI port.

Any DVI Transmitter Compliance Test results would be especially helpful.
 
Originally posted by: xtknight
Here's for the BBA X800 XT PE. It's almost certainly identical to the X850 XT. http://graphics.tomshardware.com/graphic/20041129/tft_connection-16.html
Click to expand...

yes, but how does that answer my question concerning the second transmitter?


Originally posted by: xtknight
For the (Club3D) GeForce 7800 GTX:

http://www.madshrimps.be/forums/attachment.php?postid=103152

Integrated 10 bit per channel 400MHz DAC's
Integrated 165MHz TMDS Transmitter
Click to expand...
So they're both from Nvidia?
 
Originally posted by: Ender17
Originally posted by: xtknight
Here's for the BBA X800 XT PE. It's almost certainly identical to the X850 XT. http://graphics.tomshardware.com/graphic/20041129/tft_connection-16.html
Click to expand...

yes, but how does that answer my question concerning the second transmitter?
Click to expand...

Another part of the article says:

All graphics processors currently produced by ATi and NVIDIA already come with an on-chip TMDS transmitter for DVI. Card makers using an ATi processor tend to rely on the integrated transmitter in the case of cards featuring the standard 1xVGA & 1xDVI combination. In comparison, many cards using NVIDIA's processors come with an external TMDS module (for example from Silicon Image), even though the graphics chip already incorporates a TMDS transmitter. To be able to offer two DVI outputs, the card makers always need to use a second TMDS chip on their boards, no matter what company's graphics processor they base their card on.
Click to expand...

Note the bolded text.

Originally posted by: Ender17
Originally posted by: xtknight
For the (Club3D) GeForce 7800 GTX:

http://www.madshrimps.be/forums/attachment.php?postid=103152

Integrated 10 bit per channel 400MHz DAC's
Integrated 165MHz TMDS Transmitter
Click to expand...
So they're both from Nvidia?
Click to expand...

The first is an integrated one, and the second is an external chip. Anand points that out in his G70 review here.

Layout of the card is relatively similar to the 6800 Ultra, but there are a few differences. We've still got 2 DVI slots (both single link), but the solder point for the silicon image TMDS chip for dual-link DVI is either missing or moved. We will certainly be interested in seeing a workstation version of this part.
Click to expand...

So my guess is there's a third for a second single-link DVI.

But...why? It varies by brand anyway. Remember, ATI and NVIDIA provide only reference designs. Right now you're likely to find only reference designs so you can be pretty sure what Anand says will hold true at this point in time. In the future, they may vary. Though I see no reason why the DVI circuitry would have to be changed.

If you want 2D quality, you're best off with Matrox. External TMDS chips are more prone to interference, if I recall correctly from that Tom's Hardware Guide article, and their tests showed the ATI to be better vs. the 6800 which used the integrated+external SI chip.

Edit: Sorry got a little confused there. Maybe the opposite is better, on-chip TMDS are better. I recommend you read the whole article, it's a good one. I read it too long ago to remember which way it was.

Ahh...my appologies. The X800 XT they tested was NOT dual-DVI. It had 1 DVI and 1 VGA. That explains it.
 
thanks for the info
I've decided on a Sapphire X850 XT dual DVI since I was able to find one used for $315
the integrated TMDS will be for my 2405fpw and the add-on should be fine for my smaller, second monitor
 
Originally posted by: Ender17
thanks for the info
I've decided on a Sapphire X850 XT dual DVI since I was able to find one used for $315
the integrated TMDS will be for my 2405fpw and the add-on should be fine for my smaller, second monitor
Click to expand...

well...are you a gamer? the 7800 runs circles around the x850xt in terms of games...to be honest I have no idea about the 7800's DVI quality because Tom's hasn't done any tests. that's a damn good price for an x850 xt though...if you don't want to spend $600 for a 7800 that's definitely understandable. if you don't game at all you might as well get a Matrox card or a cheap ATI with knowingly good DVI (Abit X600).
 
Originally posted by: xtknight
Originally posted by: Ender17
thanks for the info
I've decided on a Sapphire X850 XT dual DVI since I was able to find one used for $315
the integrated TMDS will be for my 2405fpw and the add-on should be fine for my smaller, second monitor
Click to expand...

well...are you a gamer? the 7800 runs circles around the x850xt in terms of games...to be honest I have no idea about the 7800's DVI quality because Tom's hasn't done any tests. that's a damn good price for an x850 xt though...if you don't want to spend $600 for a 7800 that's definitely understandable. if you don't game at all you might as well get a Matrox card or a cheap ATI with knowingly good DVI (Abit X600).
Click to expand...

I'm not a hardcore gamer, but I do enjoy playing sometimes.
The reason I got such a powerful card is because the native resolution on this monitor is 1920 x 1200.

And I can't spend $600 for a 7800GTX, especially when I was able to get a X800 XT so cheap.
The X850 XT PE does very well at this resolution, as can be seen here.
Of course it's lacking support for Shader Model 3.0 and HDR, but by the time those are really important, the RV530 should be out, so I might switch to it depending on the price and how fast it is.
 
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