Relaxing my mem timings with PLL at 1.54 and VTT at 1.14 and vNB at 1.46 caused the same issue of it booting fine, but failing to restart.
(DRAM/FSB at 333, CPU 6x)

I've been using OCCT and wPrime.

These settings allow me to boot and reboot with a value in VTT, but the moment I changed vNB from 1.26 to 1.28, it failed to restart (but this time it recovered on its own without me have to cut power at the PSU).
CPU - 6x
FSB - 333
STRAP - 333
DRAM - AUTO (1066)

vCore - 1.20
vPLL - 1.52
vFSB - 1.16
vDIMM - 1.9
vNB - 1.26
NB GLT - .625

Can anyone else really reproduce this problem, or am I really the only one?