[drueter]

Thank you for the suggestion about power, but the monitor is still not working.

I tried using a USB Y-cable to pull power from two different USB ports--both directly on the motherboard, and from a beefy Belkin powered USB hub. The results were the same: everything seems fine (LED and backlight respond properly to software control), but there is no video display.

Windows definitely sees the second monitor: I can move the mouse over to the extended desktop (though of course I cannot see the cursor or anything else on the black screen).

The only other strange thing I noticed is that Windows shows a third monitor--a Generic Non-PNP. I think that is just for HDMI out on the NVIDEA card, though only one monitor is connected. (The NVIDIA GT 630 card provides two DVI and one HDMI out on the back of the card. My monitor is connected to one of the DVI ports. Nothing is connected to the HDMI or second DVI port.)

The motherboard does have on-board video, but that is disabled and no drivers are installed.

Previously, sometimes at shutdown or startup of Windows the display would spontaneously switch to the other DVI port (with no monitor attached)--requiring the cable to be moved. I have not seen this happen with the latest NVIDIA drivers.

Also, when the DisplayLink monitor is installed and enabled, sometimes windows (such as a Windows Explorer window) seem to open on that display (though not visible). Disabling the DisplayLink monitor properly moves the window back to the working DVI-connected monitor.

Just to clarify, if I click the Identify button on the Windows Display Resolution control panel, I still don't see anything on the DisplayLink monitor. Also, to clarify, the monitor still works fine on other computers...so this is not a hardware problem with the monitor.

The operating system is Win 8 64 Ultimate, and is a fairly new / clean install without much 3rd party software installed.

Does anyone have any other suggestions?