Sorry I did not explain. I just wanted everybody to see that your motherboard has both VGA and two other kinds of connectors. This means the board itself has two video devices or a dual display video device inboard.
With most older motherboards the VGA is the built-in and any DVI is from the add-on card the user has. So you do not have an add-in video card in a PCI slot? You are using just the video outputs from the back panel of the Gigabyte motherboard. Is that right?
You have a GA78LMT-USB3.
Normally the BIOS on most motherboards wilt find the attached and make it the default display. But your Gigabyte BIOS does not automatically select the only monitor? Is that so?
Another reference:
GIGABYTE - Motherboard - Socket FM2+ - GA-F2A88XM-D3H (rev. 3.0)
www.gigabyte.com › Motherboard › Socket FM2+
Gigabyte Technology
Supporting multiple independent display outputs simultaneously, AMD Eyefinity ... Flexible graphics capabilities - Up to 2 VGA cards are supported for 2 way AMD ... of the latest AMD Fusion A-series APUs, GIGABYTE motherboards deliver an .... Please use keyword search or select the specific product category to find ..
But that is a different motherboard and is not about built-in dual display.
However, a reference on New egg seems to apply to your board.
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128565It has the DVI and HDMI interfaces, but no mention of BIOS options.
Found on You Tube:
https://www.youtube.com/watch?v=KvI4ZIgTmoIThe BIOS lacks clear and consistent screens. But watch the video and you will see there is a place to change the default output. Just rather hard to understand.