What do I need for dual monitors?

Need help setting up dual monitors that display the same thing?

• I have two HP Elite Book laptops and two HP Docking stations. Both have two monitors connected through the docking station. One via the VGA cable, the other via the DVI cable. One set up is able to project the same screen on both monitors, the other does not. It will either display on one screen, or allow me to "extend" to the second screen. Unfortunately, I do not want to extend the display. I want to "clone" the same screen and display it on both monitors. I know it can be done, as I have two identical set ups, one works, one does not. And I can't figure out why, or what can be adjusted to allow it. For the set up that does not work, if I disconnect the DVI cable from the docking station, the VGA monitor displays. If I reconnect the DVI cable, that monitor now displays, but the VGA monitor goes blank. Any assistance would be greatly appreciated!!!

• Answer:

  DVI cable is for a digital video signal, and VGA cable is for an analog video signal. Apparently, the driver software you use for the DVI signal cannot handle what you wish to do. Can you connect with an adapter DVI-to-VGA and and a VGA cable? Can you be sure you have both laptops' video drivers the same version with the same settings? http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?lang=en&cc=us&prodTypeId=321957&prodSeriesId=3688868&prodNameId=3688870&swEnvOID=2096&swLang=8&mode=2&taskId=135&swItem=ob-83838-1 is a driver download for the docking station.