Hardware KVM switch deliberations ... suggestions?

I’m looking at purchasing a new desktop PC , but its specifications will likely be so much better than my current rather old desktop PCs, that it occured to me that my 4-way KVM switch (for keyboard, VGA-Video, and mouse) may not work (as I anticipate both the new desktop and associated new monitor may only use DVI).

I currently have old 2 PCs under my desk, sharing one keyboard, video (19" TFT monitor with only VGA), mouse. Both are very old and have only VGA video output. I plan to also put the new PC under my desk, and have it share a common keyboard, video (new TFT monitor with DVI), and mouse with the two old PCs.

I’ve been struggling how to add the new PC (with new monitor) and still keep the old PCs, but not add an extra monitor to the physical desk. I’m thinking now the solution is to:

  • purchase new PC with DVI video out, and
  • purchase new 24" or 26" monitor (1920x1200 resolution) with DVI in, and
  • purchase two new inexpensive Nviida FX5200 graphic cards with DVI output, to put in each of my two older PCs (and disable those PCs on-board video that supports VGA only);
  • purchase a new 4-way DVI KVM (so I can connect 3 PCs to share one keyboard, video (DVI monitor) and mouse.

While the new KVM and new graphic cards will add a bit to the price of my new acquisition, it will mean I get to keep the same desk space.

I’ll give my current 19" monitor to my wife (and she will likely pass her 17" monitor on to one of her friends). I’ll probably also dispose of my older 4-way KVM (vga) switch.

No matter how I look at this, I think if my new PC supports only DVI out, I have no choice but to provide a DVI out for each of my older PCs (as the price for KVMs that mix DVI and VGA appear significantly more expensive than cheap graphic cards).

Does anyone have a better idea given the constraints I defined ?

My plan may be shot down before it gets to the ‘starting gates’ … Turns out the best inexpensive KVM switch our local PC store has supports only 1600x1200 DVI resolution. I want at least 1920 x 1080 (preferably 1920x1200) support. …

… possibly time to go back to the “drawing board”.

I came across another reason why my plan may not work. … When I started researching this idea:

I had assumed the Graphic cards at the local shop, that use the AGP interface, would work in both my PCs.

But I know note that my oldest PC (an athlon-1100 running an MSI KT3 Ulstra (KT133)) has an older AGP slot capable of 1x,2x and 4x (hence I believe it to be an AGP v.2.0 slot in the motherboard).

But all the new graphic cards in the local stores have AGP 8x (some AGP 4x,8x) and hence I believe them to be an AGP v.3.0 compatible.

From what I can read, an AGP v.3.0 card may not work in an AGP v.2.0 slot (even if they are both 4x), and even if they work, they could be unstable: Hardware Knowledgebase - Will my 8X AGP video card work in my 4X AGP slot? - HardwareFAQs: powered by neofaq

… hmm … I’m now giving thought to discarding this old athlon-1100 (which would be shame, as it still runs well with 1GB RAM and a 300GB hard drive).

Hmmm… you seem to be talking to yourself oldcpu :wink:

Why not use PCI then? I have a PCI e-GeForce FX5200 with 128MB RAM and
it’s vga out.

Cheers Malcolm °¿° (Linux Counter #276890)
SUSE Linux Enterprise Desktop 11 (i586) Kernel
up 2 days 16:44, 1 user, load average: 0.09, 0.19, 0.20
GPU GeForce 6600 TE/6200 TE - Driver Version: 180.35

A definite sign, perhaps, of old age and senility ? rotfl!

That was my original idea. … But that means I would need the high performance graphic card (for my planned Intel Core i7 motherboard) also would have to support vga (to use same KVM as older PC). Plus the new 24" or 26" monitor that I plan to procure would also have to use VGA. Thats a restriction that I’m not particularly keen on accepting … Most newer high-resolution TFT monitors and high performance graphic cards have only DVI. IMHO it may be better just to “dump” the old PC … but I’m not sure . …

I’ve got twin 19" widescreen Viewsonic LCD’s that have both DVI and
VGA. You could use your KVM to switch and use the VGA on the older

I prefer to use NX now and use that instead of a KVM. I also use NX on
my VM’s so I can start and just access from my notebook if required.

If I was to build a new machine, I would look at getting a couple of
50W Quad core Xeons :wink:

Cheers Malcolm °¿° (Linux Counter #276890)
SUSE Linux Enterprise Desktop 11 (i586) Kernel
up 1:20, 1 user, load average: 0.51, 0.26, 0.16
GPU GeForce 6600 TE/6200 TE - Driver Version: 180.35

Not sure I understand. You have one PC with a VGA, and one with a DVI, each connected to separate 19" TFT’s, and use the KVM for the keyboard mouse switching ?

I went thru a phase (before I upgraded the RAM from 512 MB to 1GB in my old athlon-1100) that I used to only access it via nx after booting it to run level 3. But the bottom line was it still needed the keyboard, video and mouse to boot.

… indeed.

I like the price range of a PC based in the Intel core i7 … and their performance is not bad.

Its look less and less likely that I’ll be able to keep using my old athlon-1100.

I’m also struggling to find an inexpensive KVM that supports 1920x1200 resolution.

You can press the input switch on the monitor and switch between the
vga and dvi inputs. I have had the VIA pico-itx machine connected to one
screen with it’s own mouse and keyboard for setting up. To get back to
the openSUSE machine just press the button again.

In your case you could just switch the keyboard/mouse, then press the
monitor button?

Can’t you turn off the halt on error in the BIOS? else you need to make
a dongle to plug in to the PS/2 ports to trick it into thinking the
keyboard and mouse are connected?

Cheers Malcolm °¿° (Linux Counter #276890)
SUSE Linux Enterprise Desktop 11 (i586) Kernel
up 2:08, 1 user, load average: 0.15, 0.14, 0.10
GPU GeForce 6600 TE/6200 TE - Driver Version: 180.35

Yes, I can see that would work. I’ve seen a 26" Samsung Monitor that has both a DVI and VGA input. I could use my standard VGA KVM (connected to my two old PCs) and connect it to the VGA on the monitor, … and also connect the new PC’s DVI output to the DVI input on the 26" monitor. But I think I would still need two keyboards and two mice (where one keyboard/mouse is for new PC, and one keyboard/mouse is for the KVM for the two old PCs). It has the advantage of solving the 1920x1200 KVM resolution problem. I also get to keep the old PC. … but I do have to put up with the irritation of the second keyboard and second mouse.

I think (not sure) the VGA is needed from the new computer to help power the KVM (as the KVM does not have its own power supply). Hence it may not work.

I confess I’m not particularly keen on either of these, although I should examine them for feasibility.

Thanks for the suggestions.

I use have one Pc and a Amiga computer with only one keyboard and mouse my friend.
It works at that time very well.I use the system 8years ago.
I use switch box that you can plug in 2 pc and it works for me.
But if you like a little more in advance I can look up for and tell you in future.
Other hand why not look into viewsonic N5230p 52" I will get in two month and I try out with my cable.
viewsonic N5230p 52" it is only $2500 euro.

What switch box. That term is so general. One can not pick just any switch box and put it in and expect it to function. I’ve been using a basic KVM switch (2 way, and 4-way, dependant on how many PCs I have under my desk) for over 5 years now!

One needs to pick a switch box that handles both DVI and VGA. Have you looked in to that? Have you talked to uses that have those? I have.

  1. they (combined vga/dvi kvms) are expensive (i’m not going to pay > 100 euros for a kvm or other type of switch when the old PC is not worth that much - it makes no financial sense).
  2. some of the combined vga/dvi kvms do not work reliably.

So its not a simple matter. Any kvm (or other type of switch) has to be inexpensive to make it worth considering.

If you know something more that is detailed technically, then I would be curious. But please note it can not be just any switch.

Why not? price. price. price. For euro 2500 I can purchase my new camcorder and quite possibly my new computer. I sure am not going to spend euro 2500 on a new monitor.

I hope you enjoy that monitor, … unfortunately I don’t have the luxury of that sort of money to throw at a PC setup.

It doesnt how many computer you have 5,10,100 or more it is just matter how to set it up. Today tech. is everything possible and I give one idea with a small setup 2/3 computer with a very small box I it is a small box in inches 4"x6"8" a metal box with two control,I believe one control to switch from PC and Mac/amiga or vise versa and other switch I dont remember.But it works very good.
If you like I look around and send you picture by email what ever is ok with;)lol!

You know I have lots of money to spend I don`t care of few Canadian dollars what is 20.000 euro to spend this year in germany?
Is not much money.


Technically it does not matter. IMHO financially it does matter. IMHO it makes no sense financially, to spend 300 euros to connect to a computer that is worth less than 100 euros. If you read this thread from the start, you would read that I am questioning (myself) if it is worth the money to try and keep my old computer, given the constraints I have applied (which is one new monitor, one mouse and one keyboard, to control 3 vastly different computers, where one new computer has a DVI only interface, and where one old computer has a vga only interface).

Its not clear to me from reading your posts that you understand what a kvm switch is, what DVI interface is, and what VGA is, … so some links:
KVM: KVM switch - Wikipedia, the free encyclopedia
DVI: Digital Visual Interface - Wikipedia, the free encyclopedia
VGA: Video Graphics Array - Wikipedia, the free encyclopedia

Now one can purchase kvm switches that cost thousands of euros, that can do all sorts of neat and shiny things. I will not, … I repeat, I will not purchase an expensive KVM, … ok one more time, I will not spend a LOT of money on a KVM or other switch, when the PCs I am trying to connect are not worth a lot of money. IT MAKES NO FINANCIAL SENSE.

I have 3 KVM switches in my apartment. Each cost less than 40 euros.

My research suggests this can NOT , I repeat can NOT be done cheaply if one is mixing DVI and VGA interfaces (and also handle keyboard and mouse). It is not clear to me you understood that in my post. If you know of an INEXPENSIVE (I repeat, inexpensive) way to do that reliably, with BOTH vga and dvi interfaces (and keyboard/mouse), then I would be curious.

It also has to be a reliable way. Again, my research has suggested inexpensive methods (of mixing vga and dvi (with keyboard/mouse)) do not work reliably. Again, I would be curious to learn otherwise.

I have 3 KVM switches at home (for VGA, not for DVI) and they are all small. I have absolutely no idea as to what sort of technical capability this “metal bix” that you refeer to has, although 4"x6"x8" is rather large. The KVM’s I use are about 1/3 to 1/4 that size.

20,000 ?? or 20.00 ?? There is a BIG difference.

But glad to read you have lots of money to spend on various items. I do not.


I’m not trying to second-guess your reflections or anything, but if I were you, I’d reconsider my starting points. Namely: do I really, unconditionally need to keep all that power-consuming, global-warming old junk under my desk if I’m getting a new, silent and power-efficient machine anyway? Given a state-of-the-art, fast machine, couldn’t all those tasks be achieved with virtualization? Or, alternatively: couldn’t I at least do away with the KVM switch and just use remote desktop instead? I could then either sell the old equipment, or maybe just give it to charity.
But, as I said, it is not my intention to question your line of thought. I’m sure your dilemma is based on well-grounded considerations and reasons I’m just not familiar with.

Cheerz! :slight_smile:

Indeed, and that is what I am contemplating now. Should I dispose of my old athlon-1100 (1GB RAM) with slow nVidia MX440 ? I just might.

Not really. The new PC I have planned with be running flat out rendering, with not a cpu cycle to spare for any virtualization.

I played with remote desktop for a long time. But I found the adantages of a physical KVM switch, for my use, were superior to that for accessing the PC via remote desktop. Remote desktop does have complications, when it comes to the need to provide the motherboard indication that there is an attached keyboard and video. Without that, the remote PC will be complex to boot. Plus having a separate (albeit old) PC, means one can ssh into one’s main PC, when there may be problems with the main PC. A hardware KVM is pretty much immune to one of the PCs on the KVM freezeing. But a software remote desktop is not so immune.

Indeed. Of course charity typically thumbs their nose at an old athlon-1100. They don’t want such an old PC. I’ve had a couple of charity rejections already to my tentative offer.

Reading my previous post, I realize I was a bit harsh. Apologies. But in truth, I think you will find this sort of search very tiring. I know I have. Typically the KVMs that do the sort of thing that I want cost 200 to 300 euros, or more. Thats well beyound my budget for keeping a 9-year old computer.

Also, I find the video on many of the KVMs do not support 1920x1200 resolution, and that is a MUST support for me.

This is the most flexible relatively inexpensive KVM I have found to date … although at 80 euros its a bit more pricey than I would like:
DVI S-VGA KVM Switch 4-fach, USB, Audio: Amazon.de: Elektronik

It does meet my 1920x1080 resolution requirement.

I put the German language review of this KVM into babelfish translation page and read the translated review, … The review convinced me this KVM does not have the behaviour that I need in a KVM. So strike this one from consideration.

This has me thinking … I wonder if I could connect a VGA-to-DVI adapter into my old athlon-1100’s VGA output, and then plug that DVI into a 4-way KVM (where this is a DVI KVM, and not a VGA KVM). The graphics output of the athlon-1100 does not have to be great … just marginally functional is good.

This would mean:


  • keyboard =============================>||
  • video (DVI) ==========================>||
  • mouse ================================>||…||
    Athlon 2800 … ||…||
  • keyboard =============================>||…KVM…|| ========> keyboard
  • video (DVI or VGA)====================>||…|| ========> New Monitor (DVI input)
  • mouse ================================>||…|| ========> mouse
    Athlon 1100 …||…||
  • keyboard =============================>||
  • video (VGA) ==> VGA-to-DVI adapt =====>||
  • mouse ================================>||

I’m not sure how well the above sketch/depiction will show up (re: formatting) … but thats the idea.

I now need to check if a VGA to DVI conversion is possible … (I know DVI to VGA can be done).

OK, I learned VGA to DVI can be done, but it is typically rather expensive :cry: (as opposed to DVI to VGA which is very inexpensive). :stuck_out_tongue:

Time to look now to see if I can find an old AGP v.2.0 (1x,2x,4x) graphic card that has a DVI output (the AGP cards with DVI output, in our local PC store, are all the newer AGP-v3.0 standard, which is 4x,8x, and are not compatible with my old PC’s AGP v.2.0 (1x,2x,4x)).