I get the feeling we are mixing up several different problems.
The linked thread started out talking about the memory clock problem, hence the 2D idle clocks vs. 3D clocks. Then someone mentioned tearing, which is a separate problem that can happen when mixing DVI and DP, and that's when Ken started talking about how the clocks for DVI and DP are different. That has nothing to do with the flickering.
If this is not the memory clock problem, I can only think of three possibilities:
1. The DisplayPort cable isn't good enough to handle the full bandwidth required to run the U3011 at the native resolution.
2. The DisplayPort on the video card can't actually handle the full bandwidth even though it should.
3. The DisplayPort on the monitor is not working properly.
In any case, moving the U3011 to a dual-link DVI port and connecting one of the 2007FP monitors with an active DP -> DVI adapter might work around the problem.
Originally Posted by tompsonn
My issue wasn't due to memory clocks at all
Although I am aware of the flicker you get when the clocks change *cough* loading flash videos on my 5750 *cough*
If active DP -> DVI adapters helped in your case, then mixing DVI and DP is not the problem unless you connected all three monitors with adapters because the video card would still be outputting a DisplayPort signal with an active adapter.