LR, found this in a forum, might help with you flickering problem.
've now determined that it's a driver incompatibility between the ATI catalyst drivers and my viewsonic monitor. I have tested every scenario of monitor and card combinations with a friend's peripherals. All ATI cards cause my Viewsonic monitor to flicker. All versions of the catalyst drivers do this. Are there other versions of the ATI drivers that don't involve this catalyst garbage? And I know that you can download the display driver only, but that doesn't solve the problem. Are there other third-party ATI drivers that aren't omega that anyone here has used? Thanks.
Plus
Well, after doing more research for about 3 more hours today, i found a site that gave me some glimmer of hope. They also made me realize why i REALLY hate ATI. So, it appears that the ATI drivers for the new graphics cards seem to be bad with different monitors, so you have to downgrade your card.
Catalyst Control Center
All the way to the bottom click on ATI Overdrive
Click the lock to turn on Overdrive
Where is says GPU Clock: (leave this alone)
Where is says Memory Clock: Default is like 950, you need to bring it down to 900.That removes all the flickers and gives you a glimmer of hope. Only downfall to this, you spent $300+ to get a graphics card that can be overclocked and because ATI sucks &#$@, you now have to downgrade your expensive graphics card. Your best opinion to repair this, is RETURN the card in question, get your money back, get the xfx GeForce GTX 285 or 295. Suggest going with 285 till you are 100% sure that the newest GTX 295 doesn't have any flaws. Hope this helps you.
Also have a look at:
LCD monitor technology and tests