Im wondering if the VTT/GTLREF can help me stabilize my OC w/o bumping my CPU Vcore,

Currently im using 1.335v ( bios ) for 400 * 8 on my Q6600 G0, and left the CPU VTT to 1.20v and GTLREF at 63% I can run at 1.315v only 8hours prime stable,after that 1 random core gets an error.

My temps are fine and dont hit more than 63c on a scorching afternoon.