I recently had trouble with 3D06 and a 920 clocked at 191x21 with turbo enabled. With bios 0619, there is no real control over turbo mode, and instead of going only 1 step up it does 2 when only 1-2 cores are loaded --> jump to 4,2Ghz and freeze during Deep Freeze. Really annoying issue, had to disable the turbo and run it at 200x20 which needs slightly more Vcore but doesn't freeze (better for the customer lol).