I have 2 identical 17" acer monitors connected to my HD4670 (using VGA to DVI adapters). When ever I seem to open internet explorer, send an instant message, drag a window over, etc, the 2nd monitor will flicker. Anyone with a similar problem/know what causes this? I've updated to the latest drivers and both monitors are set to 1280 x 1024 @ 75 hertz.

Why have you got 75Hz refresh rate?
In the refresh rate section tick to check 'hide modes that this monitor can not display", and then set both monitors to 60Hz

Thanks for your reply.

I did what you said (the check boxes were already checked). I lowered both to 60 hertz, but the problem is still there.

I noticed somethign weird though. After playing L4D for abotu an hour or 2 the problem seemed to be fixed. After my next reboot however, the flickering returned.

Is the flickering always on the same monitor.
Try each monitor singly (to test if its the actual monitor istelf)
The try swappling the adaptors you are using.

It only flickers on the screen that is being cloned/extended on. I tried every cable/adaptor combonation, as well as a 3rd screen. It only flickers when I open a program, switch to a program, send a message, open a new window, etc. It is prob just my video card not being able to handle more than 1 display that well. I've gotten used to it though.

I'm now wondering if it has something to do with the DVI-I on the card.
Your card has one DVI and one VGA - correct.
I am presuming that your monitors only have VGA input, and that you are using a DVI - vga adapter to connect the second monitor.

I have noticed that if in the monitor settings the monitor is set to receive VGA , and you plug in a DVI connection that it will automatically flick over to the DVI - with a bit of a flicker?

I wonder what would happen if you had a monitor with a DVI imput to connect to the DVI on the card without using the DVI to VGA adapter.

Maybee others on the forum can chip in with their ideas.

Anyhow, why do you want to have dual monitors when you are gaming.\?

I have the exact same problem as you with a flickering second display and I have gone through the same procedure as you to try to find the fault, of course, without success.

But today I managed to get rid of the flickering just by unchecking "Enable ATI Overdrive" in Catalyst Control Center.

I have a Radeon HD4850 and I'm using Catalyst 9.9 and Windows Vista Business 32-bit OS.

Dang I wish I knew that back then. Good to know now I guess. I hated that flickering it drove me nuts.

Everything works perfect in Windows 7 though, no problems.

k0rny said:


I had a similar problem with my four 28" monitor setup. I tracked the problem down to bad RAM.

Confirmed. 5770 here and i disabled Overdrive... and the flickering was cured.