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I purchased a PowerColor HD 5770 video card so I could get a third monitor working. I have two widescreen monitors, one attached via HDMI and the other attached via DVI. My third monitor is attached from DisplayPort to VGA (using a passive connector like this one)

The third monitor is a 19" Hyundai L90D. I was unable to find any Windows 7 (or Vista for that matter) drivers for the monitor, so it's stuck with "Generic Non-PNP Monitor". It's native resolution is 1280 x 1024. Randomly Windows will boot up in the correct native res, but sometimes it boots up in 640 x 480 res. When it does boot up into 640 x 480 res, the screen resolution slider is stuck and I cannot slide it back to 1280 x 1024.

I cannot find a pattern for when or why it will do this, I've tried rebooting five or six times in a row at times to get it to boot into native res, but this doesn't always work.

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what happens if you use your DisplayPort converter (it is actually active not passive, otherwise you can only operate two monitors) on the other monitors? – icelava Jun 15 '12 at 7:33

Check the monitor properties. Is "Hide modes that this monitor cannot display" checked? Perhaps that is preventing you from using the slider.

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The checkbox for this is grayed out, but it is not ticked. I cannot toggle it either way, though. – ajbdev May 4 '10 at 20:12

Sounds like either through the cable conversion process (DP to VGA) or due to the quality of Hyundai (or both), Windows 7 is not getting the information it needs about the monitor on boot-up - the monitor is not transmitting its EDID ("Extended display identification data").

Two ways you could correct that:

  1. Manually run a scan for new hardware or displays in Catalyst Control Center or Windows 7.

  2. Script-force Windows 7 and / or CCC to scan for displays on boot-up. Windows Task scheduler is an excellent tool, but before that I would check into CCC's settings.

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