Does the Dell 2405FPW support dual DVI?

[MichaelD]

Originally posted by: Chaotic42
My 2405FPW doesn't have any noticable tearing with my 7800GTX over DVI.

2407FPW here. No tearing or any other artifacting at 1920x1200 w/a 7900GTO. In fact, it's darn perfect. :heart:

 

[xtknight]

For 1920x1200, VESA General Timing Formula:

# 1920x1200 @ 60.00 Hz (GTF) hsync: 74.52 kHz; pclk: 193.16 MHz

Max bandwidth for single-link DVI is 165 MHz so I don't see how you're using 1920x1200@60Hz with a single-link connection. You are using dual-link DVI (330 MHz) and just don't know it.

Actually, on some cards 1920x1200@60 Hz is not actually running at that. So if you have single-link, it may be scaling to 50 Hz with skipping that may or may not be noticeable. This fits in spec:

# 1920x1200 @ 50.00 Hz (GTF) hsync: 61.75 kHz; pclk: 158.08 MHz

 

[mercanucaribe]

No, it's well known that it uses single link. I think it may just use 50hz. Dual link is not 330mhz. It's two 165mhz connections, or whatever. Twice as many wires.

 

[mercanucaribe]

http://forum.ecoustics.com/bbs/messages/5/84663.html

a single link DVI-D connection has a 165MHz dot clock to play with so that obviously isn't going to work, PCs have a trick up their sleeve which is to strip almost all blanking information out of the signal allowing access to resolutions beyond 1600x1200, (fwiw 1920x1200 is basically the highest standard resolution available beyond 1600x1200 which a single DVI-D link supports

What is blanking information?

 

[xtknight]

Dual-link actually is 330 MHz. See here. http://www.siliconimage.com/products/product.aspx?id=78&printme=0

Bandwidth: Single Link: 25 MHz - 165 MHz, Dual Link: 25 MHz - 330 MHz

Blanking information is the information needed to paint a new frame. I believe there are some holdovers in the DVI signal such as "move the electron gun back to the top right of the screen" and the reduce frequency option eliminates this unneeded/irrelevant information.

 

[mercanucaribe]

So dual link is 4x as much bandwidth?

 

[xtknight]

Originally posted by: mercanucaribe
So dual link is 4x as much bandwidth?

No, it is 2x as much bandwidth.

165 MHz x 2 links = 330 MHz
------------
per link

'Odd' pixel data is sent down one link, and 'Even' through the other thus you end up with twice the bandwidth.

CPU frequency is a different animal though.

 

[mercanucaribe]

Originally posted by: xtknight

Originally posted by: mercanucaribe
So dual link is 4x as much bandwidth?

No, it is 2x as much bandwidth.

165 MHz x 2 links = 330 MHz
------------
per link

'Odd' pixel data is sent down one link, and 'Even' through the other thus you end up with twice the bandwidth.

CPU frequency is a different animal though.

That's what I said in the first place. It's not 330mhz, it's two 165mhz links. Then you said it's 330mhz!

 

[zylander]

Originally posted by: Chaotic42
My 2405FPW doesn't have any noticable tearing with my 7800GTX over DVI.

Same here. No noticable tearing on my 2405fpw on a 7900gt.

 

[vhx]

Originally posted by: sm8000
Dang, not familiar with nVidia's driver options. Does it have something like "reduced blanking interval" or "alternate DVI frequency"?

http://img213.imageshack.us/img213/8874/cvtzt3.jpg
^ is that what you are talking about?

 

[Steve]

Originally posted by: vhx

Originally posted by: sm8000
Dang, not familiar with nVidia's driver options. Does it have something like "reduced blanking interval" or "alternate DVI frequency"?

http://img213.imageshack.us/img213/8874/cvtzt3.jpg
^ is that what you are talking about?

Could be, I'm solely a Radeon user so I don't know what to look for on the dark side.

 

[mercanucaribe]

Originally posted by: vhx

Originally posted by: sm8000
Dang, not familiar with nVidia's driver options. Does it have something like "reduced blanking interval" or "alternate DVI frequency"?

http://img213.imageshack.us/img213/8874/cvtzt3.jpg
^ is that what you are talking about?

How did you get that?

 

[vhx]

Custom Timings window in the Nvidia Control Panel. You have to be in the advanced view to see it.

 

[mercanucaribe]

I'm in advanced view and there's nothing like that. This is 165.01 of Forceware though.

 

[vhx]

If you are using Vista, it doesn't have custom timings yet. Otherwise it should be there.

 

[mercanucaribe]

Found it. The default option is the same as "CVT Reduced Blank".
Text

 

[mercanucaribe]

I realized that a DVI cable I had in my truck because I forgot to return it is actually dual link DVI. Unfortunately it has analog pins so I couldn't plug it into my monitor which blanks out those 4 holes for some reason!

 

[Steve]

That means the DVI port on that monitor is DVI-D only. With those holes it's DVI-I.

 

[mercanucaribe]

By filling in the holes they make it so you can't use a cable with both digital and analog, which makes no sense. There's no reason that cable wouldn't work otherwise.

 

[Steve]

Dell isn't filling in the holes on purpose, they're using a legitimate DVI connection: http://en.wikipedia.org/wiki/DVI

Ever see a Radeon 9100? That had a DVI-D only port. So I'm not sure what you're getting at exactly.

Incidentally, I was able to run my 2405 off a Radeon 9100 over DVI-D. Slowly though, as it was a PCI card. But it ran, dammit!

 

[mercanucaribe]

Originally posted by: sm8000
Dell isn't filling in the holes on purpose, they're using a legitimate DVI connection: http://en.wikipedia.org/wiki/DVI

Ever see a Radeon 9100? That had a DVI-D only port. So I'm not sure what you're getting at exactly.

Incidentally, I was able to run my 2405 off a Radeon 9100 over DVI-D. Slowly though, as it was a PCI card. But it ran, dammit!

The port can have holes without them being connected. There is no reason not to. The only thing not having the holes does is exclude the use of a DVI cable that also has analog connections. There is no reason for them to do that. I'd have to buy a new cable, or pull the 4 analog pins out of my perfectly fine DVI-I cable.

 

[Steve]

Did the monitor not come with a proper cable?