@bobruto: If I understood correctly, the multi is actually changed - at least once, down to 4x, but then raising it back to 13x fails. Try to use 'Auto' as multi in the BIOS menu and see if that works, if I recall correctly there were some reports about C&Q not working correctly if the multi is set manually. Always depends upon the BIOS implementation...

@Tiger-Heli: Thanks, glad to hear there's another happy user. About your questions:
1) You almost got it right. The problem is that if the active power scheme allows CPU throttling (such as the default 'Balanced' scheme, not just the powersaving one), standard C&Q is active if enabled in the BIOS, conflicting with custom C&Q and resulting probably in a mess (haven't tested it myself).
2) It's not about absolute or relative voltages - you change the voltage IDs (VIDs), not the actually delivered voltages. They may correspond to the actual voltages (more or less), but that depends upon your BIOS and mainboard. In your case, the BIOS adds a fixed offset to the voltage IDs; my BIOS (ASUS M3A78-T) alters the voltage IDs for P0 (but does not allow to customize the other P-states). This topic has already been covered in this thread, I think.