I have an Intel motherboard (DH67CL) that uses Intel HD 3000 video. It has two video output ports: HDMI and DVI. Both my monitors are DVI, so I have two cables: a DVI->DVI and an HDMI->DVI.
If I plug a monitor into just one of these ports, things work fine. However if I plug monitors into each of the ports, the system startup screens show on both monitors, along with the "Starting Windows…" screen, but as soon as the system boots into Windows, the HDMI-connected monitor goes to sleep.
When I use the Intel video control panel, the HDMI-connected monitor is not detected. How do I get a dual-monitor setup to work?
Best Answer
Well... first, according to the Product Specifications for your board, both the HDMI and DVI ports are enabled for POST when a monitor is attached to either (or both). So, right there, that's why they both seem to work at boot.
Furthermore, there are posts in their support forum like this one that indicate other boards like yours will support both the HDMI and DVI being used in Windows at the same time. To me, this implies that the reason why your HDMI monitor goes to sleep could be a resolution one. At least, that would be the case to me if the monitor was detected.
With this forum post, and a similar board, the issue finally turned out to be a driver based problem.