DVI switch

What aspects of a DVI switch (KVM for example) would affect its ability to handle higher video modes such as 1920 x 1200 (when it can handle 1600 x 1200)?
I'm curious why there are so many DVI switches that have a 1600 x 1200 limit and can't do 1920 x 1200.
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says...

What refresh rate? Perhaps it needs Dual Link DVI (DVI-DL) to get the refresh rate you're looking for at 1920x1200.
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| says... |> What aspects of a DVI switch (KVM for example) would affect its ability to |> handle higher video modes such as 1920 x 1200 (when it can handle 1600 x 1200)? |> I'm curious why there are so many DVI switches that have a 1600 x 1200 limit |> and can't do 1920 x 1200. | | What refresh rate? Perhaps it needs Dual Link DVI (DVI-DL) to get | the refresh rate you're looking for at 1920x1200.
1920x1200 (WUXGA) is a single link format. Single link can go all the way up to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) format would also be doable on single link. Dual link could go up to 2960x1850.
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Well, at least per the pixel clock limits on both single- and dual-link DVI, they sure could. The problem is, though, that the DVI standard never included a decent compliance certification test, nor is there any good spec on cabling, switches, and the like that would truly ensure that you can run full rates over any given comibination of such things. So as you approach the top-end clock spec, some will work, and some may not.
Bob M.
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| | \ |> |> 1920x1200 (WUXGA) is a single link format. Single link can go all the way |> up |> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) |> format |> would also be doable on single link. Dual link could go up to 2960x1850. | | Well, at least per the pixel clock limits on both single- and dual-link | DVI, they sure could. The problem is, though, that the DVI standard | never included a decent compliance certification test, nor is there any | good spec on cabling, switches, and the like that would truly ensure | that you can run full rates over any given comibination of such things. | So as you approach the top-end clock spec, some will work, and | some may not.
I called one of the makers of one of the switches I found like this (Blackbox) and the guy I talked to tried to convince me that no one uses 1920x1200. My response was "but they do use 1600x1200 when monitors of that type are rare adn hard to find and are about to go out of production because the world is shifting to widescreen so they have enough space to display 1920x1080 video?". He didn't have an answer to that loaded question. I suggested he have the product sent back to engineering.
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snipped-for-privacy@ipal.net says...

This monitor is 1920x1200. It is quite common for 24" LCD monitors.
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| snipped-for-privacy@ipal.net says...
|> |
|> | |> | \ |> |> |> |> 1920x1200 (WUXGA) is a single link format. Single link can go all the way |> |> up |> |> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) |> |> format |> |> would also be doable on single link. Dual link could go up to 2960x1850. |> | |> | Well, at least per the pixel clock limits on both single- and dual-link |> | DVI, they sure could. The problem is, though, that the DVI standard |> | never included a decent compliance certification test, nor is there any |> | good spec on cabling, switches, and the like that would truly ensure |> | that you can run full rates over any given comibination of such things. |> | So as you approach the top-end clock spec, some will work, and |> | some may not. |> |> I called one of the makers of one of the switches I found like this (Blackbox) |> and the guy I talked to tried to convince me that no one uses 1920x1200. My |> response was "but they do use 1600x1200 when monitors of that type are rare |> adn hard to find and are about to go out of production because the world is |> shifting to widescreen so they have enough space to display 1920x1080 video?". |> He didn't have an answer to that loaded question. I suggested he have the |> product sent back to engineering. | | This monitor is 1920x1200. It is quite common for 24" LCD monitors.
So when will the KVM switch manufacturers understand that 1920x1200 is a common desktop display resolution?
I found something in another model KVM switch that might indicate some possible support issues. It seems many of these KVM switches have an on screen display (the "OSD" feature). The switch will have to process the video, syncronize to it, and insert their own video, to get that OSD to work. Their logic board might not have the capability for some of the higher modes.
I don't need or care for OSD. I'd even prefer to not have it at all, for a desktop environment.
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says...

I suspect it's an excuse to cover for insufficient product planning (they didn't see the price falling through the floor on these things - $270 last fall).

Certainly possible. I've had to insert some DVI logic into the design I'm working on. The information out there certainly isn't clear. It's possible they never tested on larger formats, neglecting them because they didn't see them coming so soon.

I don't want the switch to insert anything, for sure.
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| says...
wrote: |> |> |
|> |> | |> |> | \ |> |> |> |> |> |> 1920x1200 (WUXGA) is a single link format. Single link can go all the way |> |> |> up |> |> |> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) |> |> |> format |> |> |> would also be doable on single link. Dual link could go up to 2960x1850. |> |> | |> |> | Well, at least per the pixel clock limits on both single- and dual-link |> |> | DVI, they sure could. The problem is, though, that the DVI standard |> |> | never included a decent compliance certification test, nor is there any |> |> | good spec on cabling, switches, and the like that would truly ensure |> |> | that you can run full rates over any given comibination of such things. |> |> | So as you approach the top-end clock spec, some will work, and |> |> | some may not. |> |> |> |> I called one of the makers of one of the switches I found like this (Blackbox) |> |> and the guy I talked to tried to convince me that no one uses 1920x1200. My |> |> response was "but they do use 1600x1200 when monitors of that type are rare |> |> adn hard to find and are about to go out of production because the world is |> |> shifting to widescreen so they have enough space to display 1920x1080 video?". |> |> He didn't have an answer to that loaded question. I suggested he have the |> |> product sent back to engineering. |> | |> | This monitor is 1920x1200. It is quite common for 24" LCD monitors. |> |> So when will the KVM switch manufacturers understand that 1920x1200 is a common |> desktop display resolution? | | I suspect it's an excuse to cover for insufficient product planning | (they didn't see the price falling through the floor on these things | - $270 last fall).
That well could be. Given the response I got from the rep at Blackbox, that would be consistent.
|> I found something in another model KVM switch that might indicate some possible |> support issues. It seems many of these KVM switches have an on screen display |> (the "OSD" feature). The switch will have to process the video, syncronize to |> it, and insert their own video, to get that OSD to work. Their logic board |> might not have the capability for some of the higher modes. | | Certainly possible. I've had to insert some DVI logic into the | design I'm working on. The information out there certainly isn't | clear. It's possible they never tested on larger formats, | neglecting them because they didn't see them coming so soon. | |> I don't need or care for OSD. I'd even prefer to not have it at all, for a |> desktop environment. | | I don't want the switch to insert anything, for sure.
We sure agree on that. At least for a desktop situated KVM switch box, lights on the box can do the job better at less cost. It's just a matter of passing all the signals fully and not having mechanical contacts to do it.
I have found this _expensive_ KVM switch that looks like it might do the job I need:
http://www.avocent.com/SwitchViewSC_DVI_4-port.aspx
The thing is designed for classified environments which require isolation between the 4 (or more for larger models) computer connections. OTOH, maybe that will end up with a better impedance matching of the signals, and better RFI shielding, resulting in less double-edging on analog and fewer errors in marginal conditions on digital (such as me hitting the transmit key on my 2m HT too near the computer). Still, $500+ for a 4-port KVM? Ouch!
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says...

When I was using a KVM I had it stuck under the table (until the hot-key recognition started screwing up). I never needed to look at it.

Ouch. I'd go with a virtual terminal sort of setup first. I have two sets of displays now so (when both systems were operational) I just switched the keyboard and mouse. If I could put another display on my laptop (can't get the graphics card to work in the dock) I'd be back to a KVM of some sort. It'll be a while though. The desktop system isn't working and I have no time (or interest) in "fixing" it at least until we move.

Don't do that! Ouch indeed. Way north of even my considerable toy budget.
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| | \ |> |> 1920x1200 (WUXGA) is a single link format. Single link can go all the way |> up |> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) |> format |> would also be doable on single link. Dual link could go up to 2960x1850. | | Well, at least per the pixel clock limits on both single- and dual-link | DVI, they sure could. The problem is, though, that the DVI standard | never included a decent compliance certification test, nor is there any | good spec on cabling, switches, and the like that would truly ensure | that you can run full rates over any given comibination of such things. | So as you approach the top-end clock spec, some will work, and | some may not.
Here's another one I found. It has a _higher_ resolution limit (1920x1440) but it has some suspicious words in the tech specs saying "This products is not intended for use with Widescreen displays".
http://www.startech.com/item-specs/SV421DVI-4-Port-StarView-DVI-KVM-Switch.aspx
So what could that possibly mean? Could it really be that these switches are messing around with the EDID data or other parameters affected by the specific geometry, and are not designed for the 16:10 geometries?
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To get my Samsung 20" 1280 * 960 I had to place a special order;although my graphic card (Asus ATI 2600 pro) is dual head, also comes with 2 DVI plugs, the monitor that the vendor matched, was a VGA one, so I had to use DAC->ADC with all cons. (www.cccira.gr) The order took 10 days to process, as if I was asking something exotic. Anyway, it's a good monitor.(It's widescreen). It cost 250 euros.
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|
| |> | \ |> |> |> |> 1920x1200 (WUXGA) is a single link format. Single link can go all the |> way |> |> up |> |> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) |> |> format |> |> would also be doable on single link. Dual link could go up to |> 2960x1850. |> | |> | Well, at least per the pixel clock limits on both single- and dual-link |> | DVI, they sure could. The problem is, though, that the DVI standard |> | never included a decent compliance certification test, nor is there any |> | good spec on cabling, switches, and the like that would truly ensure |> | that you can run full rates over any given comibination of such things. |> | So as you approach the top-end clock spec, some will work, and |> | some may not. |> |> Here's another one I found. It has a _higher_ resolution limit |> (1920x1440) |> but it has some suspicious words in the tech specs saying "This products |> is |> not intended for use with Widescreen displays". |> |> http://www.startech.com/item-specs/SV421DVI-4-Port-StarView-DVI-KVM-Switch.aspx |> |> So what could that possibly mean? Could it really be that these switches |> are |> messing around with the EDID data or other parameters affected by the |> specific |> geometry, and are not designed for the 16:10 geometries? |> |> -- | To get my Samsung 20" 1280 * 960 I had to place a special order;although my | graphic card (Asus ATI 2600 pro) is dual head, also comes with 2 DVI plugs, | the monitor that the vendor matched, was a VGA one, so I had to use DAC->ADC | with all cons. (www.cccira.gr) The order took 10 days to process, as if I | was asking something exotic. Anyway, it's a good monitor.(It's widescreen). | It cost 250 euros.
What I'm trying to do is switch from among 4 computers, 2 with HD15 analog video out, and 2 with DVI-D out. I want to run the DVI ones at 1920x1200. The analog ones would be at some lower 16:10 resolution, and be scaled up. The quality is not critical for the analog ones, but they need to at least maintain functionality without major distortion. Output from the KVM switch would go to a DVI-I to DVI-D + HD15 splitter, and both of those go into the same monitor. That way when the switch selects a DVI machine, digital video goes to the monitor, otherwise the monitor just gets analog.
It needs to also have PS/2 keyboard/mouse without any use of USB conversion.
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says...

At 60Hz, yes. By 85Hz single link is out of gas. That was my point ("what refresh rate?"). Do follow along.
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| says...
|> | says... |> |> What aspects of a DVI switch (KVM for example) would affect its ability to |> |> handle higher video modes such as 1920 x 1200 (when it can handle 1600 x 1200)? |> |> I'm curious why there are so many DVI switches that have a 1600 x 1200 limit |> |> and can't do 1920 x 1200. |> | |> | What refresh rate? Perhaps it needs Dual Link DVI (DVI-DL) to get |> | the refresh rate you're looking for at 1920x1200. |> |> 1920x1200 (WUXGA) is a single link format. Single link can go all the way up |> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) format |> would also be doable on single link. Dual link could go up to 2960x1850. | | At 60Hz, yes. By 85Hz single link is out of gas. That was my point | ("what refresh rate?"). Do follow along.
I will push the refresh rate as low as I can make it work. The lowest monitor found will go down to 48 Hz (from HP). If I stick to the literal WUXGA format, then it's 60 Hz. For the computers outputting the 1920x1200, the vertical rate isn't much of an issue. The analog computers will be outputting some lower resolution to be scaled up, and at the lowest refresh rate I can get (because that gives me some more resolution on those).
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says...

???
I don't think I'd care too much for 48Hz, though have never tried it. My laptop/24" monitor combination is restricted to 60Hz (at 1920x1200). I thought it was because this is a cheap monitor (which I suppose is true - single link).

"Analog computers"? "Scaled up"? I don't understand the entire paragraph.
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| says...
|> | says...
|> |> | says... |> |> |> What aspects of a DVI switch (KVM for example) would affect its ability to |> |> |> handle higher video modes such as 1920 x 1200 (when it can handle 1600 x 1200)? |> |> |> I'm curious why there are so many DVI switches that have a 1600 x 1200 limit |> |> |> and can't do 1920 x 1200. |> |> | |> |> | What refresh rate? Perhaps it needs Dual Link DVI (DVI-DL) to get |> |> | the refresh rate you're looking for at 1920x1200. |> |> |> |> 1920x1200 (WUXGA) is a single link format. Single link can go all the way up |> |> to 2098x1311 for odd formats. 2048x1152 (non-standard, but sensible) format |> |> would also be doable on single link. Dual link could go up to 2960x1850. |> | |> | At 60Hz, yes. By 85Hz single link is out of gas. That was my point |> | ("what refresh rate?"). Do follow along. |> |> I will push the refresh rate as low as I can make it work. | | ???
I don't need the refresh rate. I'm not doing fast action gaming. My use of computers is programming, building Linux pseudo-distros, and managing some web servers. While I would use 75 Hz refresh on a CRT to avoid flicker, I don't need to do that on LCD. I have no need to run it even as high as 60 Hz. 24 Hz would be fine by me if I could find a monitor that would accept it.
|> The lowest monitor |> found will go down to 48 Hz (from HP). If I stick to the literal WUXGA format, |> then it's 60 Hz. For the computers outputting the 1920x1200, the vertical rate |> isn't much of an issue. | | I don't think I'd care too much for 48Hz, though have never tried | it. My laptop/24" monitor combination is restricted to 60Hz (at | 1920x1200). I thought it was because this is a cheap monitor (which | I suppose is true - single link).
At 48 Hz, the DVI clock rate can go lower, compared to 60 Hz, for the same geometry (e.g. 1920x1200 on each). The clock rate for 1920x1200 at 60 Hz could do 2048x1280 at 52.75 Hz. Or it could do 2560x1600 at 33.75 Hz. You just need components (video driver, video card, KVM switch, monitor) that don't insist the video mode match one of the named VESA standard modes.
|> The analog computers will be outputting some lower |> resolution to be scaled up, and at the lowest refresh rate I can get (because |> that gives me some more resolution on those). | | "Analog computers"? "Scaled up"? I don't understand the entire | paragraph.
Sorry for the confusion.
By "analog computers" I meant "The two computers I have here that output their video in analog as RGB over a HD-15 connection" ... as opposed to the "digital computers" which are "the (other) two computers I (will) have here that output their video in digital as RGB over a DVI connection".
The computers that output video in analog won't be at 1920x1200. They may be at 1440x900. I'll live with the upscaling artifacts. They are currently running at 1200x960 into a 1280x1024 monitor. The catch is that the highest number of video lines I can program into them is 1023. That and I cannot find a newer video card that supports the software I use on those machines (maybe in the near future the ATI Radeon ones will have enough info released I could upgrade the software for).
Two new computers (one is built now, but I have not selected the video card to go to 1920x1200 for it, yet, so it's limping along as a server for now at a video geometry of 1152x864) will become my new primary graphical desktops. The intention is to go with 1920x1200 but I'm open to doing 2048x1280 or even 2560x1600 if I can find a monitor that will do it at a slow enough speed to do it over ONE DVI link channel. Some monitors will go down to 50 Hz or 48 Hz, so it's just a matter of finding one with 2048x1280.
BTW, that's another of my common rants ... monitors that have LOW frequency limits on vertical video frame rates that are higher than an existing standard video frame rate (e.g. 23.976 Hz). They just need to have a clock that can be adjusted to a lower rate and firmware that doesn't assume all video is at a higher rate.
Have a look at the tech specs on THIS monitor:
http://pro.jvc.com/prof/attributes/features.jsp?model_id=MDL101671
It is intended for broadcast studio purposes, but can be used as a computer display (as can so many TVs out there). It does support 23.976 Hz in the 3xBNC component inputs. But it doesn't support 23.976 Hz in the HD15/VGA input. I don't see why it shouldn't, though. Apparently it can do the component in either YPbPr or RGB, so I'm curious how well it would do if I used a VGA to 3xBNC connector to feed the computer video that way.
I know that going FASTER is hard to do. It requires better clocks and faster digital circuits. It requires analog amps with a higher bandpass. But why is going _slower_ hard to do, too?
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| says... |> What aspects of a DVI switch (KVM for example) would affect its ability to |> handle higher video modes such as 1920 x 1200 (when it can handle 1600 x 1200)? |> I'm curious why there are so many DVI switches that have a 1600 x 1200 limit |> and can't do 1920 x 1200. | | What refresh rate? Perhaps it needs Dual Link DVI (DVI-DL) to get | the refresh rate you're looking for at 1920x1200.
I suspect what the switch might be trying to do is mess with the EDID data. And its firmware isn't coded for more than 1600x1200. I just don't know if this was because the engineer coding it didn't know of 1920x1200 (unlikely) or if management interfered (more likely). Maybe it could be a documentation issue and it really would work with 1920x1200.
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| says... |> What aspects of a DVI switch (KVM for example) would affect its ability to |> handle higher video modes such as 1920 x 1200 (when it can handle 1600 x 1200)? |> I'm curious why there are so many DVI switches that have a 1600 x 1200 limit |> and can't do 1920 x 1200. | | What refresh rate? Perhaps it needs Dual Link DVI (DVI-DL) to get | the refresh rate you're looking for at 1920x1200.
How about this one?
http://www.startech.com/item-specs/SV421DVI-4-Port-StarView-DVI-KVM-Switch.aspx
It has a max resolution of 1920x1440. But it also says it is not intended for widescreen displays.
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