# External screen shaking

I have an ASUS K53SV laptop with NVidia Optimus: integrated Intel graphic card + NVidia GT540M. I just upgraded to Fedora 17 and I have a weird problem with some external screens. I did have similar problems with Fedora 16 too, but not with the screen that is driving me nuts now, which is shaking and makes hard working.

I tried installing Bumblebee and bbswitch to get rid of the discrete card and eventually turn it off when I don't need it. I then noticed there are different kinds of shaking, depending on:

• Power cable connected, discrete card ON => shaking a lot
• Power cable connected, discrete card OFF => shaking a lot
• Power cable disconnected, discrete card ON => shaking
• Power cable disconnected, discrete card OFF => shaking a little

Well, this seems the most common behaviour, even though it can change in a random way. For example sometimes it shakes a lot with power cable disconnected, and if I connect it it shakes less. That's weird.

I tried different screens and the behaviour still seems pretty random. With some screens I have similar problems, with some it works fine. I tried changing the VGA cable too, but the problem is still the same.

Even more weird, I just found out that while I have the power cable connected, the worst situation, the screen stops shaking if I run a command like grep -ir something *, that would make me think that when the cpu is busy, working pretty hard, the problem disappears. As soon as the process has done, the screen starts shaking again. Please, don't think I'm crazy :) I made several tests!

Do you have any suggestion how to fix this issue?

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