|If you are using a DVI to VGA gender adapter in a DVI port for a monitor with a VGA plug (15 pin d-sub) on the end of it's video cable, make sure the adapter is all the way into the DVI port, and that it's screws are securing it to the posts for the port. Or try a different DVI to VGA gender adapter - they're cheap to buy locally if you don't have another one to try. |
Make sure that there are no bent pins in the plug on the end(s) of the video cable for the monitor. If any are bent, straighten them using something slim, pivoting whatever you use at the base of the bent pin for the best chance of not breaking off the pin.
If that doesn't apply, or if that does apply but doing that doesn't help, if you can unplug the video cable at the monitor end of the connection, try a different video cable (you may need to buy one).
If that doesn't apply, or if that applies but doing that doesn't help, there's something wring with either the monitor's circuits or the video cable for it.