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I recently bought a second monitor to run a dual screen set up on my PC. My first monitor is an HP 21" 1600x900 resolution 5ms latency, 60hz refresh rate, LCD. My new monitor is a 23" H1920x1080 resolution 2ms latency, up to 75Hz refresh rate, LCD with LED backlit.

Both monitors are set to 60Hz, and each to their max resolutions (stated above) and they each work fine when they are plugged in seperatley. But when they are both plugged in at the same time, the screens will randomly flicker and/or tear. Not super frequently but frequently enough to be annoying. And only when I am using Windows.

My graphics card is an XFX ATI radeon 5770.

What is causing this issue?

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You say "only when using Windows". What other operating systems have you tried? And do you actually mean a Radeon HD 5770? –  nhinkle Sep 26 '11 at 23:39
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Have you tried updating the Radeon drivers to the latest ones? –  mauvedeity Oct 8 '11 at 10:49
    
I didnt mean the operating system itself, but instead I ment operating on the desktop or not in a game / window that was fullscreen, but recently I found that the blue line appeared at all times. And yes I tried the most recent drivers, and rolled them back as well. The strangest thing though is that the blue line went away. Again. So now it has appeared, dissapeared, appeared, and dissapeared. It is currently not on my screen anymore so I hope it stays this way. –  kenetik Oct 10 '11 at 17:05
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1 Answer

is your power supply strong enough to provide enough power? It could be well possible that your graphics card needs a lot of power but you don't notice anything as long as only one monitor is plugged in. But then, once you plug-in the second one, there's not enough power. Could be a possibility. How many Watts does your power-supply provide?

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Yes, I have a 750w PSU and the max load of the ATI Radeon HD 5770 is 450w. I dont think the monitors, motherboard and fans could bring that all up to 750w. But it is a good idea, I will check all of the wattage today. As I mentioned in my last comment, the blue line went away again, and I don't know why.. But I hope it stays away. –  kenetik Oct 10 '11 at 17:06
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