Screen tearing, duplicated screen HD5850

I have the same problem, actually every HD5800 series owner has the same problem. Its something to do with the 2d desktop graphics. The out of the box ram seed on the cards are to so slow for 2 screens, well at least that's what i read on the net.
so to permanently change your 2d graphics to run 2 screens like it should out of the box follow these steps.

1. find C:\Users\"name"\AppData\Local\ATI\ACE\Profiles
you will have to turn on "see invisible folders" in your folder options in Control Panel\Appearance and Personalization

2. One you have found that directory open up ATI catalyst and at the top right click options/profiles/Profile manager

3. make a new profile and save it but DO NOT activate it. Now go back to the profiles dir and click on the new file that you must made.Its an XML file should be able to open it word pad

4. now it looks like this :
<Profile>
<Caste name="Graphics">
<Groups>
<Group name="Overdrive5">
<Feature name="TimeUnlocked" />
<Feature name="OverclockEnabled">
<Property name="OverclockEnabledProperty" value="True" />
</Feature>
<Feature name="AutoTuneSupport" />
<Feature name="CoreClockTarget_0">
<Property name="Want_0" value="40000" />
<Property name="Want_1" value="55000" />
<Property name="Want_2" value="77500" />
</Feature>
<Feature name="PowerControl_0">
<Property name="Want" value="0" />
</Feature>
<Feature name="MemoryClockTarget_0">

Now change the memory clock, i forget the orignal values but here mine

<Property name="Want_0" value="110000" />
<Property name="Want_1" value="110000" />
<Property name="Want_2" value="112500" />

once they are changed save the file and activate the profile in CCC and you should see the mem clock go up to whatever you set it at in the xml file. you will have to play around with the mem speed to find the best results. hope this helps i know that flicker is so stupid especially when they are tying to market 3 screen technology at least get 2 screens right.

If any one else has some other ideas or comments or if there was something i mist tell me i would like to know more.

Thank you for the advice. I tried what you suggested. Do I understand correctly that basically these changes mean I am overclocking the video-card's memory?. I am kind of surprised this is required to achive 2 screen normal performance but o well..

Unfortunately modifying the Want_0 value to match the Want_1 value had almost no effect on the video quality. Since my numbers in the profile.xml file were lower than yours to begin with (90000 instead of 110000) I was hesitant to raise the numbers further without consulting the forums first on what it might mean / cause. I would not want to burn out my card after all.

Also - in this case we are changing the speed of the memory as I understand. Have you yourself tried modifying the GPU clock as well or has it been determined already that the memory clock is the main showstopper?

Thanks again.

Late reply, but I had the same problem and found this thread... and another solution without overclocking the card memory, so if this can help someone else :

My config is :
Windows 7 64 bits
CPU Intel I7-860
Mobo Gigabyte P55A-UD4
GC Asus 5850 DirectCu
Screens 2xLG L245WP

I was experiencing tearing on my videos (mainly HD720p & over) but only with my second screen (right), all was ok with the left one (set as main screen in Windows).
I launched CCC and swapped the screens configuration (left & right inverted) : the problem disapeared !
Of course, now my Windows desktop was also left/right inverted so I swapped also the screens in the Windows config panel and the problem remained solved.