Re: video for NEC 4100
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Posted by Paul on May 21, 2008, 1:08 pm
Please log in for more thread options DVI digital has a thing called the "dot clock". By specification, it maxes out at about 165MHz, while if you examine what is on the cable with a scope, you see signals at 1650 megabaud. Which is damn fast. The extremely high speed, is what helps limit the cable lengths supported. There are a few video cards, where the DVI output is not capable of reaching full speed. The driver prevents the resolution from going too high, in order to prevent the DVI output from appearing "snowy" to the user. That could be a reason for restricting the output. When I was looking for cards, I read a comment about the 9250 chip, which said that the second DVI connector would only do 1024x768. And that is really restrictive, in terms of the 1920x1200 res that DVI should be able to do. http://en.wikipedia.org/wiki/Dvi The VGA is limited by the video DAC (digital to analog converter) bandwidth. The bandwidth specification of the DAC, determines the resolution and refresh rates that can be supported. One reason for the grainy look, could be a resolution mismatch and resampling happening on the monitor. That tells me you aren't really running at 1360x768. The display should look better, if you can manage to drive it at "native" resolution. And DVI should look a bit better than VGA, because with VGA, any imperfections in the cable (electrical reflections), are visible on the screen. DVI is perfect, until bit corruption flips individual bits, and then you see "snow" start to appear. If transmission is really bad, maybe eventually you lose sync. With the goofy 1366x768 thing, monitors have displayed a number of strange looking symptoms. On some of them, it is virtually impossible to strike a video output resolution, that the monitor likes. I believe the more modern ones, are a bit more tolerant of the 1360-1366-1368 variations. For example, if the monitor is sent 1360 and is 1366 internally, it should just use black bars for 3 pixels on either side of the picture. But some of the old ones, would try to resample the image and scale it, which looks stupid. There are apparently some video cards that have resolution to the nearest pixel (so you could dial up 1366 if you needed it), but there is no way, using the available advertising material, to find such cards. And since your monitor is supposed to accept 1360, an ordinary card (divisible by 8) should suffice anyway. Paul | |||||||||||||
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Posted by sid on May 21, 2008, 9:47 pm
Please log in for more thread options > sid wrote:
> > > Lots of info !
> > The Compaq and HP SFF have a riser card for the PCI slots, so the PCI > > cards sit parallel to the main board and don't have to be short. =A0Only= > > the AGP card has a slot that makes it sit perpendicular to the main
> > board and so it has to be short. >
> > The Radeon card that I have supports: DVI 1376x768 =A0and =A0VGA 1600x12=
00
> > I was just wondering why the VGA supported higher resolution than the
> > DVI ? > > And if a new card could push the resolution even higher ? > > What looks nice on a 20" looks pretty grainy on that system. >
> > Also, Any way to divide the screen up ? =A0Make the PC think that this
> > one screen is actually many screens ? >
> > Thanks
>
> DVI digital has a thing called the "dot clock". By specification, > it maxes out at about 165MHz, while if you examine what is on the > cable with a scope, you see signals at 1650 megabaud. Which is damn > fast. The extremely high speed, is what helps limit the cable > lengths supported. > > There are a few video cards, where the DVI output is not capable > of reaching full speed. The driver prevents the resolution > from going too high, in order to prevent the DVI output from > appearing "snowy" to the user. That could be a reason for > restricting the output. > > When I was looking for cards, I read a comment about the 9250 chip, > which said that the second DVI connector would only do 1024x768. > And that is really restrictive, in terms of the 1920x1200 res that > DVI should be able to do. > > http://en.wikipedia.org/wiki/Dvi > > The VGA is limited by the video DAC (digital to analog converter) > bandwidth. The bandwidth specification of the DAC, determines the > resolution and refresh rates that can be supported. > > One reason for the grainy look, could be a resolution mismatch > and resampling happening on the monitor. That tells me you aren't > really running at 1360x768. The display should look better, if you > can manage to drive it at "native" resolution. And DVI should > look a bit better than VGA, because with VGA, any imperfections > in the cable (electrical reflections), are visible on the screen. > DVI is perfect, until bit corruption flips individual bits, and > then you see "snow" start to appear. If transmission is really > bad, maybe eventually you lose sync. > > With the goofy 1366x768 thing, monitors have displayed a number > of strange looking symptoms. On some of them, it is virtually > impossible to strike a video output resolution, that the monitor > likes. I believe the more modern ones, are a bit more tolerant > of the 1360-1366-1368 variations. For example, if the monitor > is sent 1360 and is 1366 internally, it should just use black > bars for 3 pixels on either side of the picture. But some of the > old ones, would try to resample the image and scale it, which > looks stupid. > > There are apparently some video cards that have resolution to > the nearest pixel (so you could dial up 1366 if you needed it), > but there is no way, using the available advertising material, > to find such cards. And since your monitor is supposed to accept > 1360, an ordinary card (divisible by 8) should suffice anyway. > > =A0 =A0 Paul- Hide quoted text - > > - Show quoted text - Paul and Grinder, I want to thank you for you responses. =46rom all the I have read, my conclusion is that upgrading the card and the PC would not show a significant benefit. Right now we have the monitor displaying some WebPages that monitor critical applications. The pages only update every few moments and what we have does not even seem to be taxed. I will plan to upgrade in the next few months, but I don't see urgency to rush an upgrade in the next day or so. Thanks Sid. | |||||||||||||
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Posted by sid on May 22, 2008, 9:49 am
Please log in for more thread options >
> > > > > > sid wrote:
>
> > > Lots of info !
ly
> > > The Compaq and HP SFF have a riser card for the PCI slots, so the PCI > > > cards sit parallel to the main board and don't have to be short. =A0On= > > > the AGP card has a slot that makes it sit perpendicular to the main
> > > board and so it has to be short. >
> > > The Radeon card that I have supports: DVI 1376x768 =A0and =A0VGA 1600x=
1200
> > > I was just wondering why the VGA supported higher resolution than the
> > > DVI ? > > > And if a new card could push the resolution even higher ? > > > What looks nice on a 20" looks pretty grainy on that system. >
> > > Also, Any way to divide the screen up ? =A0Make the PC think that this=
> > > one screen is actually many screens ?
>
> > > Thanks
>
> > DVI digital has a thing called the "dot clock". By specification,
> > it maxes out at about 165MHz, while if you examine what is on the > > cable with a scope, you see signals at 1650 megabaud. Which is damn > > fast. The extremely high speed, is what helps limit the cable > > lengths supported. >
> > There are a few video cards, where the DVI output is not capable
> > of reaching full speed. The driver prevents the resolution > > from going too high, in order to prevent the DVI output from > > appearing "snowy" to the user. That could be a reason for > > restricting the output. >
> > When I was looking for cards, I read a comment about the 9250 chip,
> > which said that the second DVI connector would only do 1024x768. > > And that is really restrictive, in terms of the 1920x1200 res that > > DVI should be able to do. >
> >http://en.wikipedia.org/wiki/Dvi
>
> > The VGA is limited by the video DAC (digital to analog converter)
> > bandwidth. The bandwidth specification of the DAC, determines the > > resolution and refresh rates that can be supported. >
> > One reason for the grainy look, could be a resolution mismatch
> > and resampling happening on the monitor. That tells me you aren't > > really running at 1360x768. The display should look better, if you > > can manage to drive it at "native" resolution. And DVI should > > look a bit better than VGA, because with VGA, any imperfections > > in the cable (electrical reflections), are visible on the screen. > > DVI is perfect, until bit corruption flips individual bits, and > > then you see "snow" start to appear. If transmission is really > > bad, maybe eventually you lose sync. >
> > With the goofy 1366x768 thing, monitors have displayed a number
> > of strange looking symptoms. On some of them, it is virtually > > impossible to strike a video output resolution, that the monitor > > likes. I believe the more modern ones, are a bit more tolerant > > of the 1360-1366-1368 variations. For example, if the monitor > > is sent 1360 and is 1366 internally, it should just use black > > bars for 3 pixels on either side of the picture. But some of the > > old ones, would try to resample the image and scale it, which > > looks stupid. >
> > There are apparently some video cards that have resolution to
> > the nearest pixel (so you could dial up 1366 if you needed it), > > but there is no way, using the available advertising material, > > to find such cards. And since your monitor is supposed to accept > > 1360, an ordinary card (divisible by 8) should suffice anyway. >
> > =A0 =A0 Paul- Hide quoted text -
>
> > - Show quoted text -
>
> Paul and Grinder, > > I want to thank you for you responses. > From all the I have read, my conclusion is that upgrading the card and > the PC would not show a significant benefit. =A0Right now we have the > monitor displaying some WebPages that monitor critical applications. > The pages only update every few moments and what we have does not even > seem to be taxed. > I will plan to upgrade in the next few months, but I don't see urgency > to rush an upgrade in the next day or so. > > Thanks > > Sid.- Hide quoted text - > > - Show quoted text - If I install an AGP card, can I still enable the on-board graphics adapter and run another monitor ? I want to know the pro/con of using AGP vs PCI. | |||||||||||||
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Posted by Paul on May 22, 2008, 10:20 am
Please log in for more thread options sid wrote:
>
> If I install an AGP card, can I still enable the on-board graphics > adapter and run another monitor ? > I want to know the pro/con of using AGP vs PCI. > The average answer to that question, is "No". On some computers (like some of the latest PCI Express motherboards), you can keep the built-in graphics on the motherboard, enabled at the same time as a card you've added. But the majority of computers don't seem to allow it. So I wouldn't depend on that capability. Remember, that the AGP card will be able to drive two monitors. So, with the built-in disabled, you should still be able to connect two monitors to the new AGP card. One difference between the cards, is bandwidth available at the connector. So this shows why some flavor of AGP will be a help. PCI - 133MB/sec AGP - 2133MB/sec for AGP 8X 1066MB/sec for AGP 4X 533MB/sec for AGP 2X 266MB/sec for AGP 1X PCI Express x16 - 4000MB/sec bidirectional, total 8000MB/sec - (Bidirectional, because PCI Express has two busses, TX and RX) Say you wanted to update a 1280x1024 rectangle on the screen, 30 times a second. The color mode could be 32 bits per pixel, meaning 4 bytes to color one dot. Think about how many megabytes per second that would be. That is when you don't want the PCI card, as you need plenty of bandwidth to do something like that. That might represent some kind of movie playback. For many purposes, the PCI card would be fine. But there will be pathological cases I can suggest, where the PCI card will suck. Paul | |||||||||||||
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> Lots of info !
> The Compaq and HP SFF have a riser card for the PCI slots, so the PCI
> cards sit parallel to the main board and don't have to be short. Only
> the AGP card has a slot that makes it sit perpendicular to the main
> board and so it has to be short.
>
> The Radeon card that I have supports: DVI 1376x768 and VGA 1600x1200
> I was just wondering why the VGA supported higher resolution than the
> DVI ?
> And if a new card could push the resolution even higher ?
> What looks nice on a 20" looks pretty grainy on that system.
>
> Also, Any way to divide the screen up ? Make the PC think that this
> one screen is actually many screens ?
>
> Thanks