Kvm + Nvidia card - Monitor blinks + blank screen

[ozgal]

Hi there,

I need some help regards problem with monitor display blinking and then going blank after initial start up screen when using kvm switch between two computers. Both computers have CRT monitors (Samsung and Fujitsu). The kvm switches are the VGA/PS2 types.

Computer 1 is a Pentium 4 with a Gigabyte P4P800-E Deluxe mobo and 1.5GB RAM, Nvidia GeForce FX5200 + XP Pro.
Computer 2 is Duo Core (Conroe 6300) with ASRock 775Dual-VSTA mobo and 2GB RAM, NVidia MX440 + XP Pro

Have tried two different kvm switches (Laser & Wise - in Australia - did not find much info on net about them).
Both kvm switches worked okay when initially set up but on rebooting the P4, the Duo PC monitor only displayed up to Windows Logo, then went blank/power indicator blinking. Unable to reboot Duo PC normally,had to use VGA in start up mode. Finally had to reinstall drivers (i.e. uninstalled display drivers on/then reinstalled after bootup).

This also happened a few months back but at that time the P4 had an Nvidia MX400A card. Had same blinking monitor/blank screen issue - but on the P4 at that time. NVidia MX400 actually died on me, so replaced it with Nvidia FX5200.

Now it's the Duo with NVidia MX440 card with blinking monitor/blank screen, etc. But at least graphics is still alive.

Have tried Googling on problems with NVidia graphics cards/KVM switches. Seems there might be issues with NVidia but I'm not knowledgeable enough to undertand just what that is. Am wondering if next step might be to use ATI Radeon cards rather than Nvidia? (I do use Photoshop occasionally).

If anyone can help I'd be very grateful.

[Lstclair55]

Is the KVM box only capable of a certain resolution / refresh rate, etc?

[ozgal]

Hi,

Been doing some further net searching on this issue. I've found something on Wikipedia that I think sounds like the problem I'm having. I've underlined the particular paragraph that seems most relevant.

Passive and Electronic switches
KVM switches were originally passive devices based on multi-pole switches and some of the cheapest devices on the market still use this technology. Passive switches usually have a rotary knob to select between computers. They typically allow sharing of 2 or 4 computers, with a practical limit of about 12 machines imposed by limitations on available switch configurations. Modern hardware designs use active electronics rather than physical switch contacts with the potential to control eight thousand computers on a common system backbone.

A limitation with physical switches is that any computer not currently selected by the KVM switch does not 'see' a keyboard or mouse connected to it. In normal operation this is not a problem but while the machine is booting up it will attempt to detect its keyboard and mouse and either fail to boot or boot with an unwanted (e.g. mouseless) configuration if they are not detected. Thus passive KVM switches are unsuitable for controlling machines which may reboot automatically e.g. after a power failure. Most active electronic KVM devices provide peripheral emulation, sending signals to the computers that are not currently selected to simulate a keyboard, mouse and monitor being connected. These are used to control machines which may reboot in unattended operation. Peripheral emulation services embedded in the hardware also provides continuous support where computers require constant communication with the peripherals.

This at least in theory, seems to describe what I'm experiencing, i.e. the PC not actively being accessed via the KVM is not seen at startup. Why this is happening (if this indeed is the problem) is somewhat baffling, though. Both of the KVM switches I've tried look to be modern electronic devices, plus to the best of my knowledge they seem to be hot pluggable, which I understand to mean you can connect/disconnect them from the kvm switch without having to power down the computer. If this is the case, then I would think the kvm switch should operate in such a way that both pcs, regardless of which one is currently activated via the kvm, should be visible during the boot up time when BIOS is involved. (Note, that even though I use the term BIOS I have absolutely no knowledge of what/how it performs functions - I've just read that it is involved in the start up process).

Weird and not so wonderful stuff. Has me scratching my head, to say the least. :confused

Any thoughts you might have on this are of course greatly appreciated.

[ozgal]

Hi there Luke,

The laser kvm unfortunately has no instructions or box (was an ebay purchase).

But the Wise Auto Kvm Switch has a box. It looks like it is manufactured in Singapore. I purchased this from a "no-frills" type store with Asian owners who had poor English skills.

On the back of box it says:

2/4 port kvm switch is compact size design, easy portable
Support Microsost Intellimouse, Logitech Net Mouse, etc
Support DOS, Win3,X, Win95/98/98SE/2000/ME/XP/WinNT, Netware, Unix, Linux
Hot Plug - Add or Remove Connected PCs for maintenance without powering down
Very High Video Quality - Up to 1920 x 1440 Bandwith:200MHZ
No software required - easy PC selection via Push Buttons. Hot keys.

Not sure about refresh rate - no information on that. I have checked on both PCs via "NVidia Control Panel". This shows the refresh rate to be 60Hz on both PCs.

One thing I did notice though, was that the MX440 (older model graphics card) is AGP4x with 32MB memory, whereas the more recurrent model FX5200 has AGP 8X and 128MB memory. I wonder if this could possibly have anything to do with things, as it is the computer with the older card (the MX440) that failed to boot up properly, i.e. blank screen after Windows Logo displayed. In addition the card that also failed previously - on my Pentium 4 at the time - was an even older model card, i.e. the MX400 (which most likely has similar properties to the MX440).

The fact that both of the earlier model cards were on the computers that had blank displays and blinking power indicators on the monitors seems to indicate something amiss perhaps. But I'm just not sure if that's the case or if so, what the problem might be. Hopefully someone might be able to shed light on this for me.