I have a Radeon 5450 which has two outputs, and I'm using both of them. All 5450s have a third output, but some of them have an HDMI output, and some of them have a DisplayPort output. The DisplayPort output can be used to run a 3rd monitor with a certain adapter. Mine has an HDMI output, so no dice. But, my computer also has an integrated video output that is turned off by default. Can an integrated video output be used in addition to a videocard to support 3 monitors?
Perhaps... depends upon the BIOS. If BIOS doesn't support, then no. Many computers support 2 PCIE video cards... either 2, x16 or 1, x16 + 1, x1.
Maybe this would work: Plugable USB 3.0 to HDMI / DVI Adapter for Windows and Mac OS X 10.8.3 Multiple Monitors up to 2048x1152 / 1920x1200 http://www.amazon.com/Plugable-Mult...200-DisplayLink/dp/B007L6NYAO/ref=pd_sim_pc_1
Unfortunately, the answer is NO. In order to support 3 monitors, you will need another display adapter. The USB adapter seems to be you best choice. The other choice is to replace your existing display adapter.
Those do work but the picture quality is not great. Also if adding monitors and video cards either internal or external, make sure you upgrade your power supply unit otherwise you can ruin the hard drive. I learned that first hand.
?? Monitors have their own power supply. The computer's concern is with the power requirements of the video card.