VGA - DVI - KVM Dilemna

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I have had a computer failure that has caused me a dilemma until I can
find the money to replace the defunct computer.

Up until the failure,  I had two desktops connected to a IOGEAR  USB
KVMP switch, and things were working just fine even with the
complication that each desktop was multi-boot allowing me to change
from XP to W7 to W8, with minimal problems, using the desired

What I thought I could  do is move the XP and W7 hard drives from the
defunct desktop to two 'oldie'  desktops I had in the closet.  Problem
is - one of the 'oldies' only has VGA.  The other has DVI.  The latter
connects nicely to the KVM DVI cables, and I have enabled the  W7
drive to run okay there.  The former VGA 'oldie', however, will not
connect to the KVM cables of course which are DVI.  I  do have a
VGA-to-DVI  adapter that I thought should allow me to connect the VGA
output of that 'oldie' to a KVM DVI cable.  Alas, the monitor is
blank.  I should add that a second VGA monitor I have kept around
shows the  XP output from that 'oldie' correctly.  So there is VGA
output.  Doesn't make it through the KVM, though.

What can I do?  I hope I explained things correctly.

Thank you


Re: VGA - DVI - KVM Dilemna wrote:
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A DVI-I to VGA adapter is a passive device. All it is doing, is
picking up the analog signals off the "blades" portion of the
connector, and wiring them to the VGA pins.

The DVI-I connector on a computer, carries both digital and analog
signals. Using the DVI-I to VGA adapter, allows picking off the analog
signals. Using the DVI connector as is, gives access to the digital signals.
And that's why those adapters exist, passive adapters that
solve a different problem than yours.

The KVM is not any kind of "universal converter". So you would expect
a DVI KVM to be "purely digital". It would be a lot more expensive
if it had a passive adapter, converted VGA signals to DVI or whatever.

Sticking a new video card in the VGA machine, a video card with a DVI
connector, might be one way to fix it. You need to look in the VGA
machine, for a free card slot, to figure out what to buy.

There are 12 AGP cards on Newegg. Verify there are drivers for your OS.
I think it's possible a 6200 is still operable in Windows 8. Maybe not
in Windows 8.1. And it might work in an older OS. There are even older
designs, using ATI 7000, but that might be appropriate if you were
running Windows 98 or 95 or something.

EVGA 512-A8-N403-LR GeForce 6200   AGP 8X   $43

There are 57 cards in the PCI section. A lot of machines will
have PCI slots, but they're the lowest performing slots. These would
be your very last choice in a video card (you'll be cursing under
your breath the whole time). I keep an FX5200 PCI around, to be
used when flashing the video BIOS on a better card, and I don't
normally leave that card as the only video in a computer.

This model also happens to be a 6200, but plugs into a PCI slot.

EVGA 256-P1-N400-LR GeForce 6200   PCI  $40

You can learn a bit more about the AGP choices, on here.

The very best deal you could expect on a video card, would be
one for $30, also including the possibility of a small rebate.
So when I identify the ones above, they're not the absolutely
cheapest ones.

If you attempted to purchase an active adapter device of some
sort, it probably isn't going to be any cheaper than a cheap
video card. Due to the conversion ICs used in monitors and
TV sets, there are some capable chips around that can do
conversions, and the chips are reasonably cheap. It all depends
on what kind of profit the maker wants, as to whether
you get a slice of the cheapness.

This one is $36 on Amazon, but is going in the wrong direction.
It converts the digital signals on a DVI-D (digital only) connector,
to VGA analog. Close, but no cigar.

This one is going in the right direction, but I can't find a price.

Boxes like that (just based on formfactor), they sell for $100 to $300.
It wasn't that many years ago, that stuff like that was $300. But
the Startech I could find, hints that they could be made cheaper
if they wanted. Maybe if I spent a few more hours, I could find
one. I don't expect the thing though, to beat the video card
on price, and that's because of the small volumes of those
that they sell. Video cards, they make millions of those a year,
so the price comes down a bit.

There are USB video cards.

This is USB3 to DVI. More than a video card. And your old PC
won't have a USB3 connector. Using USB3, allows decent performance.
You can almost watch movies with this, without being totally pissed
off at the results.

This one is USB2 to DVI. Still costs a bit more than a video card.
And at USB2 rates, even with data compression by your processor,
driving data over the cable, watching movies is close to impossible.
This is the kind of device you use for PowerPoint slides off a laptop
that has no other video connectors. It's good for static displays
with not a lot of action. USB3 helps, in that the cable rates are
a lot higher.

So to me, a video card is the preferred means. Just a matter
of tracking down what OS the video card supports, at the same
time as looking for the cheapest one you can find. If I though
an active VGA to DVI was readily available, I'd recommend that,
but that might take several hours of searching to find something.
With a danger it would end up being $300 instead of the $36 it


Re: VGA - DVI - KVM Dilemna

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Thank you Paul - U gave me much to think about.


Re: VGA - DVI - KVM Dilemna

On 7/23/2013 4:12 PM, wrote:
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The problem might be with your monitor, and not the KVM.  My Iogear  
GCS-1104 purports to pass analog through, but I've not been able to take  
advantage of that because of my monitor.

Run the line with the VGA-to-DVI adapter straight to the DVI monitor.  
If that does not work, a monitor with a true DVI-I might.

Re: Re: VGA - DVI - KVM Dilemna


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Good idea.  I tried a direct connect,  by-passing the KVM.  The
monitor still will not display.  Whether the DVI port on the monitor
is DVI-I or DVI-D, I don't know.  Have to check that.



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