Clear monitor on DVI, blurry on VGA input.

TimTim Southwest PA Icrontian
edited October 2007 in Hardware
My hardware - Abit NF7 mb, 1 GB PC3200, Barton 2500+ oc'd to 2.2 (11x200), ATI Radeon X700 Pro 256 MB video card.

Monitor - Samsung Syncmaster 204B, almost 1 year old.

My monitor has a nice clear image when running the DVI video cable from my computer.

But I do some computer repair work on the side, and only have 1 monitor right now, so when I get a computer repair job I need to hook up my 4 port KVM switch and run my monitor on normal VGA cables, since the KVM has only VGA video ports.

When I do this, the monitor gets blurry. Not a lot, just a little, but enough to be distracting. Playing World of Warcraft at 1600 x 1200 like this is not a good idea, the blurry video is very distracting.

I was wondering if this is normal for trying to run a good LCD monitor on VGA cables, or not. If so, it really shows me the quality difference between VGA and DVI, but it could also have something to do with the $15 KVM I got off eBay a year or so ago.

I'll be picking up a second monitor for computer work, as having to swap around video cables like this is a pain, plus I can't play WoW while making extra money on computer work.

Comments

  • Your-Amish-DaddyYour-Amish-Daddy The heart of Texas
    edited October 2007
    Well the difference between DVI and VGA is that VGA is analog only. DVI can do both on the same cable, if you have all 29 pins. For LCD's this means that the entire thing can be digital, and can run up to about 9.1MB/S for your signal. VGA's original cap was 1280x1024, but it was slightly extended by increasing the clockspeed of the digital to analog converter. If you want clear picture, you go DVI. If you want compatibility, VGA's the way. Since your LCD has DVI, it should've came with a DVI cable, and you should be using that.

    I posted a long thing back on the old icrontic when I was having LCD troubles, and I did a comparitive bandwidth and featureset thingy. I can't find those resources right now, but DVI is better.
  • leishi85leishi85 Grand Rapids, MI Icrontian
    edited October 2007
    but i think it's probably due to your cheap KVM switch
  • Your-Amish-DaddyYour-Amish-Daddy The heart of Texas
    edited October 2007
    That's totally possible too. I didn't think of that.
  • LeonardoLeonardo Wake up and smell the glaciers Eagle River, Alaska Icrontian
    edited October 2007
    but i think it's probably due to your cheap KVM switch
    Yup, that is the reason!

    YAD, I cannot argue with your post. You are correct - DVI is definitely superior. But what Tim is describing is 90% likely due to the KVM. I've seen a number of what should be perfectly good VGA/AGP monitors on KVM looking like crap.

    Tim, are you running an external power supply to that KVM, or are you depending on the PS2 inputs for power?
  • TimTim Southwest PA Icrontian
    edited October 2007
    The KVM has no power source of its own. And I'm only using the KVM for the video, each of the 2 computers has a seperate mouse and keyboard wired directly to the computer itself.

    That's not a great setup, but the KVM is only in use to share the single monitor when I have a computer in here for work. Normally my main system has its own mouse monitor and keyboard all hooked up to the computer itself with no KVM.

    Also, I normally run my LCD monitor on 1024 x 768 resolution, it only gets changed to 1600 x 1200 for playing WoW. And on 1024 x 768 it is still blurry.

    What does a KVM need power for anyhow? Isn't it just a box that switches between different computers?
  • Your-Amish-DaddyYour-Amish-Daddy The heart of Texas
    edited October 2007
    Well, signal strength deteriorates over distance. The further the signal has to go, the less power it has to actually go with. Good KVM's are powered. Little plug goes into the wall and that. Also, Powered KVM's are also made with better components, and eliminate noise in the signal.
  • LeonardoLeonardo Wake up and smell the glaciers Eagle River, Alaska Icrontian
    edited October 2007
    What does a KVM need power for anyhow? Isn't it just a box that switches between different computers?
    Some KVMs will switch the signals between two computers without the need for an external source. Others loose signal quality without an external power source. Don't know why. It's just that way.
  • TimTim Southwest PA Icrontian
    edited October 2007
    One thing I've learned about this particular KVM switch - When you start up or restart a computer that's connected to it, the KVM HAS to be on the channel for that computer until the computer boots up the operating system. Otherwise it won't work.

    Then you can switch back and forth between channels for however many computers are connected to it.

    Don't know if other KVMs are like that or not, this is the only one I've ever used.
  • LeonardoLeonardo Wake up and smell the glaciers Eagle River, Alaska Icrontian
    edited October 2007
    Yes, other KVMs can be like that. KVMs are very finicky devices, especially the lower cost DVI models. I have a DVI KVM at home. The monitor display is excellent for both computers, but on restart, I have to disconnect the DVI cable from the opposite computer in order for the restarting computer to register with the KVM. Once the affected computer is completely booted, then I can reconnect the cable from the other computer and swatch back and forth between them. The high quality DVI KVMs are quite pricey.
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