Well after a few months not only did my E8400 require more volts but also my motherboard. Managed to get my system stable again @ 500x8 but needed to bump my cpu to a rather high 1.41 from 1.39 and also my northbridge from +0.125 to +0.325:

Stepping Q744a:



Even though this chip needs loads of volts for 4GHZ, it seems to run fairly cool under the Arctic Freezer 7 Pro and there are no issues with the core sensors. Ive seen loads of newer E8400's running with way less vcore but are reaching far higher temperatures! Seems to be that newer chips run hotter but need less vcore.

I am using a new beta bios that was sent to from Gigabyte for my board that fixes the DPC latency issue, my system has real low latency now, can run audio with a latency less than 1 and my system feels really snappy on the whole. Beta bios works fine with no bugs. Here is my latency now: