I have a 22 inch widescreen and a 19 inch box monitor connected via DVI and VGA cables to an ATI Sapphire HD5450 graphics card. When I choose to extend the desktop onto the box monitor, I have a flashing black line on the screen. This only seems to appear while I'm using the computer - at idle it is a clear screen. I have duplicated the screen and there isn't a problem - only when I extend the desktop from monitor 1 to monitor 2. Anyone know how I can fix this?
hm... dont know if this will work
but you can try going to catalyst control and disable overdrive if it is enabled
just uncheck the box by the overdrive
I had this problem today, same card (2nd day of using it on a dual monitor), but I'd not touched overdrive. However, after reading this I selected 'default' in CCC settings (couldn't see a 'disable overdrive' option) and...
Great tip thanks. My guess is that when I increased the refresh rate from 60 to 75Hz on one of the monitors it must have triggered an overdrive function and didn't reset it when I reverted to 60Hz.