Blurry image when connecting computer to HDMI and VGA simultaneously

Question

I have some problems with my ASUS HD 5770 with sony 42' LCD TV. The first I connect my pc and the TV by HDMI cable, it works all good, the tv image looks all right. But after I connecting my PC to the TV(by HDMI) and my monitor(by VGA) at the same time. The TV image suddenly became blurry after a while. After that no matter how i changed TV or pc display settings, the TV image was always blurry even if I connect it only. And the wrost thing is that, after windows startup, in login screen, the tv will be no display and show 'out of range' error.

I found that this only appears during windows loading screen and it looks ok during displaying BIOS info. I have tried linux too, and I have the same blurry image but no 'out of range'.

Is it the TV not compatible with the graphic card or something?

Answer 1

Often a system will force set the refresh rate and resolution of the other displays (usually related to the multi monitor settings, since it generally is more usable if all displays have the same resolution).

After connecting both displays to your PC, in Windows, check to see what the refresh rate and resolution of your TV is being set to.

(These instructions assume Windows 7, but it works with minor differences in 8 and 10)

Right click on your desktop and go to Screen Resolution, click on the screen that represents your TV, Advanced Settings, and click on the Monitor tab. Examine what you have for "Screen refresh rate". Generally it's set to something like 60Hz.

Make sure that you have the "hide modes this monitor cannot display" setting checked, and then change the dropbox to any of the other available settings. If it's not 60hz, change it to that. If it's already 60, try any other setting.

Your TV should blank out the moment you hit Apply or OK, and a prompt will appear asking you if you can see the screen. If you cannot, don't touch anything for a few seconds, and the display will reset to the old settings.

Also check your resolution - I'm going to guess that your monitor has a lower resolution than your TV (the TV is probably 1920x1080), and the computer is forcing the TV to display at the lower resolution. You can change that from the previous screen.