look who posted it
Considering this is Nvidia, who simply refused to let home users use many of the dual monitor features because they reserved it for business cards only, for a couple years I can't remotely take any criticism of Ati's dual monitor's seriously considerings something they've supported far more widely for far longer than Nvidia.
Two things to try, disable crossfire using the Catalyst AI set to default, should disable it anyway. Do this also from a fresh boot, as soon as you get to the desktop open Gpu Clock tool and change the clocks to the default 3d clocks( 725/1000 iirc) and press the set clocks button. Use GPU-Z to watch the current speeds, GPU clock tool should(till a reboot) disable powerplay and stop any clocks from dropping.
Is the second monitor still flicking around like a git when you've done that. For me and several other 5850/70 users powerplay is playing havok at the moment, with some peoples problems being fixed by mobo bios updates.
For me several small but irritating problems were fixed by disabling powerplay, and while I do like the uber low idle power usage, being at overclocked speeds all the time doesn't actually raise the idle power usage by that much so till new drivers fix it I'm happy to do so.
It will be a bit more difficult because I'm not sure if GPU clock tool can fix powerplay on both cores or not.
try it with one disabled anyway, if it fixes the flickering try to set both cores clocks(in gpu clock tool you should be able to bring down a list of the cores at the top, change to the other core and set the other to the same clock). Hopefully that could fix it, powerplay being stopped fixed my problems with dual monitors and flickering aswell as a couple other issues.
It seems perfect timing with powerplay is dropped in speed isn't being handled perfectly at the moment.
The other option you have, if of course your main display as a dvi port aswell, is to run both monitors on DVI as it might be an issue with various timing of different connection types, its worth trying various setups though.
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