There are dangers in making blanket statements. The OP was talking about adding video card(s) for a desktop. If you pick a video card that looks likes this: http://www.hitechreview.com/it-prod...finity-6-edition-graphics-card-is-here/23286/ Then yes. I will double check on the power requirements and possibly change to a higher rating power supply. If you have a video card that is like EVGA 8400GS (I have been recommending that for trading): http://www.evga.com/Products/Product.aspx?pn=01g-p3-1302-lr This is not much of a concern.
I would assume the usb 3.0 adapters deliver a much higher quality picture than the usb 2.0 making the extra cost for the 3.0 worthwhile Can anyone confirm this?
http://www.microcenter.com/product/360065/USB_20_to_VGA_Adapter I use that on my catch-all machine and I can't tell which monitor is connected to the video card vs. the USB adapter. I'm just running charts, excel, etc so maybe a difference if gaming, video, etc.
It looks like you are using the SIIG USB-to-VGA pro adapter, which runs the DisplayLink Manager software. There is an easier way than unplugging and plugging in to test which monitors are hooked up via USB. (Assumed Windows 7)... in your lower right (notification area), find the icon the represent the DisplayLink Manager software. (Looks like a monitor tapping on to a network.) Left click on it. There should be a pop-up. Use it to turn off a particular adapter. You will see which screen goes blank. Afterwards, turn it back on to "Extend".
cheap easy way to run 3 monitors is to use NVidia gt640 GPU , Less than 100 bucks and wont require a PSU upgrade in the majority of cases .
USB external video card http://www.amazon.com/s/ref=nb_sb_s...+video+card&sprefix=usb+external+vide,aps,243
I could care less which one is running off the usb. My point was I have not seen any difference in picture clarity using the usb stick. Now if you're running games, videos, etc it could be a different story.