Acer 6800 - Manual (Page 46)

4 Setting up your computer 38
Connecting a monitor
To connect a monitor, simply plug the monitor cable into the monitor port
(blue port) located on the rear panel of your computer .
Note: When a VGA card is added to the PCI Express slot, the
monitor should be connected to the add-on card and the
onboard VGA will be disabled.
Note: Refer to the monitor manual for additional instructions
and information.