I am using plugable UD-3900. Connected my 2 monitors succesfully via plugable UD 3900, but when i try to connect my 3rd monitor using USB To VGA adapter and its drivers to the device(mentioned in below link). I get error stating " You cannot use the 3rd party drivers as there is conflict between current display drivers and install drivers and suddenly my two working monitors also stop working.
Unfortunately the issue you mention is not solvable due to fundamental compatibility issues between the different types of USB graphics chipsets on the market. When using USB graphics, all of the devices must use chipsets from the same manufacturer (the three primary competing technologies are from DisplayLink, MCT, and J5. DisplayLink is far and away the leader in this technology).
Devices with different brands of USB graphics chips cannot be mixed and matched, as the drivers are not compatible with each other. (We do mention this in our USB dock and adapter listings, but realize it can be missed: “Cannot be mixed with non-DisplayLink USB graphics adapters and drivers (e.g. MCT, j5, or SMSC).”)
So if possible, your best approach will be to return your current USB to VGA adapter, and purchase a model which uses a DisplayLink chip instead, as that should be compatible with your existing drivers. (Note that all of Plugable’s USB graphics devices use DisplayLink, but many other manufacturers do as well.)
