Hokay; so I had the problem that on the main battle screen some elements flicker and don't render correctly; for example the "mount fuji" end-of-season buttom in the bottom right isn't rendered at all (just a hole where the mountain icon would be, occasionally some horizontal lines) - of the general portraits in the bottom left when clicking on an army or settlement can be replaced by other graphical elements (for example the "way of the sword / way of chi" icons) - or the background of the "advisor" geisha flickers.
I've tried numerous ways to fix it (more on this later) with no luck.
I'm using a Radeon HD6990, and I've tried the following with no progress whatsoever:
1. Installing latest drivers (both catalyst - up to 11.7 now; and the south-bridge).
2. Verifying the game cache in steam (finds 4 files that it needs to reacquire, but doesn't do anything with them)
3. Changing all of the in-game graphics settings (it still happens no matter what graphics quality I set, low, medium, ultra-high, whatever - all the same problem. Changed around all the settings in there, no joy).
4. Changing all of the catalyst global settings (turning on different levels of AA, turning on Morphising AA, setting AA quality to super-sample, turning of AMD optimised tesselation, setting AMD tesselation to application controlled, turn that off again, etc etc,)
5. Disabling Avast's 8 anti-viral shields.
6. Closing Asus's Evo Turbo unlocker and EPU power management - for some reason Shogun 2 was causing their UIs to be restored in the background; but even with them fully exitted, same problem arises.
And a few other things too.
Not sure what is left to try. One other interesting symptom is that the "flickering" goes from being sporadic and a generally mess to very quick even when I turn on Vsync. This makes me think that for some reason the game and the display hardware (the radeon and / or the monitor) aren't synching up properly, or that they're not applying the correct refresh rate (native at 85hz; would be happy to run it at 75hz).
Is there a way to force the game to refresh at 75hz to eliminate this as a possible cause?