This post may be helpful if you do have dual monitors connected to your desktop or laptop computer. There may be many issues due to which secondary monitor may not work and hence this post will give you an idea on how all the dual monitor setup works and how you can figure out what may be wrong and possibly fix it as well. Also an important note here is that as the author is not aware of your operating system, physical things about your computer such as cables connecting computer to monitor, actual monitor state, etc etc, the information given below must be taken for reference only and do anything only and only if you do fully understand and take responsibility for your actions. In case you are not sure of the information provided here, ask a friend or post link of this post on other website to understand the information given here about dual monitor.
The Computer works with two programs, one is called BIOS and one is called the Operating System. A Computer starts with a program in BIOS and then hands the control over to Operating System. Now in case you do have a dual monitor graphics card connected to your computer and your secondary monitor is not working, there is something wrong somewhere and broadly speaking there can be a hardware or software problem.
- Power Connection from Power Supply to Monitor : Hardware Problem as Power Cable may not be well connected to the Secondary Monitor, does your monitor has a LED displaying power state?
- Data Cable connection from Computer to Monitor : Hardware Problem as the cable from computer to secondary monitor may be loose or any of the two ports of the data cable or port of graphics card may be loose or broken.
- Something wrong with BIOS Settings : Can be categorised as Software Problem as the BIOS settings can be changed easily by a person who fully understand the BIOS setting to be changed. The BIOS settings may have an option to select the display device, also remember that if you have connected an extra graphics card to your desktop computer’s motherboard, then the mother board’s port would be disabled automatically and you will have to connect the monitors to the ports of graphics card.
- The Monitor itself may be broken : This can be categorised as Hardware problem. Is your Monitor Powered ON ? Does it has indicators to show monitor power state and whether it is connected to computer and receiving data? On Computer Startup, does it displays the boot sequence?
- The Graphics Card may be non functioning : In case the graphics card is broken you may not get display on any of the connected monitors or you may get display on primary monitor and no display on secondary monitor, it is really hard to say.
- There can be some settings issue or driver related issue in the Operating System : This Software problem can be figured out by asserting whether the problem is really due to a display driver or something like that. In case you have a Windows computer, power on the secondary monitor, make sure that it is well connected to the computer and start your computer in safe mode (by keep on pressing F8 when the computer starts) and check whether you do get display on secondary monitor or not. If you do get display on secondary monitor (might be in clone mode), then there may be some incorrect display setting or some display driver causing the issue.
There can be any other issue as well if your secondary monitor is not working. In case it was working previously, try to remember what changes you have done to the computer (if any) or you can even look for the problem in sequence at all the above said places. Also you may consider checking given below things with your computer
- Does the Secondary Monitor displays the boot sequence when it starts up? In case yes it does shows up the booting sequence (information about computer manufacturer, etc), then probably there may not be any hardware problem with your secondary monitor or associated hardware such as cable connections, graphics card, etc. In case the secondary monitor does not shows up the booting sequence, then you might need to make sure that the monitor is powered on and well connected to the computer at the appropriate port to the computer or if you are well versed with the cable connections and you do have an extra monitor or laptop to which you can connect the monitor and check whether there is any issue with dual monitor graphics card or monitor, it might save you a lot of time finding the problem due to which your secondary monitor is not working. Do not do change to your computer, cables, monitor or anything else if you are not sure and fully confident about the changes. In case you do have a friend who knows about computer’s cable connections to monitor and has done already, ask him / her for a hand.
- The Software issue can be solved with understanding of the problem and then finding the solution itself. Have a re look at Display Settings of your computer. In case you can change the display mode to clone mode, give it a try. In case the secondary monitor does not work even in clone mode, find out whether the secondary monitor is detected by the operating system in display settings or hardware list, you might need to update display drivers.
All above information is for reference purpose only. Do not make any software or hardware change to you computer unless you are really sure and confident about the change.