Ok.
I tried with F3, F4, F6A.
Each one detects 667 instead of 800.
Now I have F4. In Intelligent Tweaker I can set manually all the memory parameters, including speed. Now is 3.3xFSB, should I try 4xFSB?
I'm just thinking; if the newest Bios still detects 667 maybe the mainboard "knows" that the 2 pairs will not work well with 800 (with that hardware I mean, on other mainboard could work). Or maybe it detects wrong...
What do you think...?