So the final report after set of tests:
1. DX9.0c flickering
DirectX 9.0c games may still flicker under very specific circumstances. Some games may still show "flickerspots" where chance of encountering this bug will be much higher.
When taking into account Mantle and new technology, in case of DX9.0c we are talking about proper legacy support. So far DX9.0a and b games had no issues, DX8 games were OK as well. DX7 engines and older not tested.
2. Not enough resources for older games
There are two types of this bug.
a) Due some reason which is related to OS the games are stuttering, while GPU remains on 300/150Mhz.
This bug was caused by OS, root cause was not found.
b) Driver downclocks GPU and VRAM in scenes which are not very intensive.
This has been observed in Skyrim, Lakeview manor. This is also related to specific ingame situations and settings. Result is stuttering, but behavior may vary. If GPU is overclocked, such behavior leads to crash (game, driver, PC depending on level of OC), even in case that system is stable under higher load.
3. CCC window get black when operating with Video settings
Present since 12.11 betas.
4. CCC may offer unsupported resolutions
In my case it was confirmed at 1600x1200, was not present with "GPU scaling".
I havent found no new bug in last few days, so this list is final. 1 and 2 might be related.
Xeon X3360, Asus Rampage, Gigabyte HD 7970OC, Corsair HX-650