You should need be adjusting your CPU Voltage. Don't touch the CPU VDD Voltage. You may very well need to bump the CPU Voltage to 1.45v-1.475v. I can run completely 24/7stable @ 3.8 (200x19) with CPU Voltage set to auto and it registers in CPU-Z as 1.386v during full load, 1.392v @ idle. BUT, When I set the CPU Multi to 20 for 4.0ghz I have to set my CPU Voltage in Bios to 1.48v. In Windows it will register @ 1.472v at idle and at full load it bounces back and forth every few seconds between 1.456v and 1.464v. So that may be your issue.
Edited by Nightcrawla - 5/10/10 at 7:14pm