I have two video cards which display similar/same symptoms, but I am not sure the problems are related at the root as the cards are quite different and in different systems - one an AGP ATI Rage Pro in a Mac G4, and the other a PCI nVidia geForce FX5200 in a Via EPIA-M motherboard. For both it seems that in low resolution basic VGA resolution -- i.e. 640x480x16 colors -- they work just fine and about as well as expected. Once drivers are installed and higher resolutions are achieved, the cards periodically (several times a minute) blank the picture on the monitor, and the monitor acts as if signal is lost. It is very quick, but exasperated by the fact I'm using an LCD monitor, so it takes about 2 seconds for it to re-display the image. Therefore I'm not actually sure how long the signal is gone, but I'm sure it's fractions of a second. For the FX5200 it doesn't seem to matter how long the machine is on, its just periodic and random, happening a few times a minute starting about a minute after power on. For the Rage Pro it gets worse the longer its on, going from once or twice a minute at power on, degrading to the point where my LCD monitor is only flashing a brief snapshot of the image before blanking again after 5 minutes or so from power on. Needless to say, it's extremely frustrating and these computers are nigh unusable.

I'm wondering what the community's thoughts are on possible causes and solutions for this type of behavior... and, yes, I have checked all connectors for tightness and cards are inserted well. They do go through a KVM, but other computers connected to the KVM are fine (indicating the monitor is fine) and, indeed, bypassing the KVM and connecting directly to my monitor yields the same results.

One of my first thoughts is it is heat related, but I'm quite sure that they're fine... the heatsinks on both cards do not get excessively warm... never to the point where I can't keep my fingers on them for a few seconds, and I would expect different results, like artifacting, if it was heat related?

Any thoughts or ideas at this point would be greatly appreciated.