Awesome! Just curious - did you check the voltage of the separate lines via mobo software or whatever while loading the system? I wasn't getting any crashes when using the quad core + 7750, but the 12 volt line was dropping as lower than 11 volts. Very bad for the voltage regulators on the mobo.
Don't think I'm having any issues if I am to believe the monitoring software (it shows the vcore moving around). I stay above 11.95v. As you mentioned earlier I think the main issue is that I only have 6 amps on the 12v line, since the crashing immediately goes away once I limit the TDP.
Impressively, my mushkin ram undervolts to 1.35v and counting. I will see how low they will go.
My i5 2400 sips power undervolted to 1.04v at stock settings (at most ~40W) so if Gigabyte ever adds vcore to the Z77N, I'll be in good shape with the i7 3770.