I have just installed Win8.1Preview.

The monitor LG L226WTQ with native resolution 16801050 is not detected by Win8.1Preview.

The same monitor is detected by Win8Pro (also by Win8 release Preview) correctly on exactly the same hardware.

Win8.1Preview classifies my monitor as Generic Monitor non PnP, with resolutions different from the LG L226WTQ native resolution.

How do I make Win8.1Preview detect correctly, the monitor LG L226WTQ and its native resolution 16801050?

It may be a Display Driver Problem. I am not sure about it. But try installing latest drivers !

The latest display driver (offered by Windows Update) is 172MB big, so it'll takke much time in my system. Any way, in previous Win 8 version, the monitor was correctly detected immediately after the OS was installed (no need to install any update). I'm downloading the new driver, but because of previous behavior, I don't think the issue will be solved.

Thanks.

Do you have a disc ?  Or you can also try changing your drivers from device manager. Try then reply me. I will be glad to know if it works !

No, there's no discs. This system is dual booting Win8Pro and Win8.1ProPreview (in a VHDx). In Win8Pro, the NVIDIA software downloaded and installed the latest drivers automatically, so I don't have any copy of it.

But interestingly, I checked the Win8.1ProPreview info about the display driver, and the OS detected correctly the on board video card, but, in the long list of display resolutions, the 16801050 resolution is not listed! Maybe this an OS issue.

The above is for Microsoft Basic Video Adapter (or something similar in english), so the OS did not detect my video adapter. However, the Windows Update is showing a driver update for my real video adapter (NVIDIA GeForce 6150SE nForce 430). So, I must first install this update (that wasn't necessary in previous Win8 versions).

And the frequency (64Hz) is wrong for my adapter.