That's the power of the D0...

It is really amazing the OC they can achieve....It's not fair to compare a C0 stepping with a D0... Basically they achieve 4.0GHz with 1.18~1.2V... which means better temperatures... thats normal for the D0.

So, check if you are stable at these settings... Then try to reduce the voltages.. One step at a time, always checking stability...

Is this CPU VTT voltage the one set in BIOS or the one read in Windows?

I'd start reducing in this order:

IOH VCore -> IOH/ICH I/O -> QPI PLL Vcore-> 2.1 CPU PLL VCore -> ICH VCore

These aren't the most important voltages for 200 BCLK, so I think you can get them a little lower...

The try reducing the VTT, if the 1.425 is the one set in BIOS. If you get a 00000000124 BSOD, try setting the PCI-E at 103MHz. This BSOD is usually insufficient vtt or pci-e. Sometimes can mean vcore as well.

And keep going !