Always use the white DVI cable if your video card accepts it. Never use both cables at once (unless you are connecting to two different computers).

Thank you for your answer.

Do you know what are the differences between those 2 cables and the way information exchange is handled ?

Is it a question of speed, robustness ?

Jacques

DVI is a digital interface. As such it is 100% accurate. The VGA interface is analog -- subject to noise, ghosting, and jitter. Since the LCD display itself is digital, using a VGA cable means that the video card must convert digital signals to analog (for the cable) and the monitor then converts the analog signals back to digital. Using DVI eliminates both of these steps.

Thank you very much for this clear answer.

Jacques

 

talmy, I read your post with interest as I had just received a new 4600 with radeon 9800 pro and fp1901 monitor.  My monitor came out of the box with the blue cable attached and works fine that way.  I switched cables and was not able to see anything but a test pattern on the monitor. Do I need to enable this somehow and how do I do that if I can't see the screen? I'm a newby so I hope these questions aren't too dumb.  Thanks

Can't speak directly to your problem because you have a different video card than I do (I bought a Matrox G550 dual head card because my system came with a card without DVI) as well as a different monitor. But here's what I've seen:

The card senses what monitors are connected when turned on. So once you have turned on the system, you can't change the cables. Also make sure you don't have both cables connected at once. You may have to press the input select button on the monitor -- some monitors only seem to seek when turned on (my father's Samsung 191T won't auto-select once it is running).

Bottom line is -- turn off both computer and monitor while changing cables. Then turn on the monitor before (or simultaneously with) turning on the system.

 

thanks, I'll give it a try .

All is good now.  Thanks