My system is stable with all version bioses, all 2.0 and 2.4B multipliers. It's just that memory bios settings are not working corectly in any bios version.

Tested F3 bios and I didn't got any improvement. Although 2.5 strap is working in F3, is not better then 2.4.
F3 bios version is missing 2.66 strap.
Back to F7.