Thought I'd have a go at maxing
CPU tried 9x510 as that had been stable at 8.5.
Benches
Stability

Spent a good while trying different settings to try and stabilize
CPU. Consistently failing with core 1, spent a while tweaking gtlref maximum I got was 10min small fft with core1 gtlref at 0.625v. Trying either side of this value produced only 2min runs.
Bios settings as
4,335 8.5x510 400/1,333 = 1,701 6-6-6-14
Except:-
Code:
Voltage Setting - Sub Menu
CPU VID Control..................: 1.4125v
CPU VID Special Add Limit........: Enabled
CPU VID Special Add..............: Auto
DRAM Voltage Control.............: 1.89V
SB Core/CPU PLL Voltage..........: 1.55V
NB Core Voltage..................: 1.361V
CPU VTT Voltage..................: 1.343V
Vcore Droop Control..............: Enabled
Clockgen Voltage Control.........: 3.45v
GTL+ Buffers Strength............: Strong
CPU GTL 0 REF Volt...............: 0.635
CPU GTL 2 REF Volt...............: 0.625
CPU GTL 1 REF Volt...............: 0.625
CPU GTL 3 REF Volt...............: 0.625
NB GTL 0 REF Volt................: 0.610
NB GTL 1 REF Volt................: 0.610
FSB Vref.............................: 00
CPU Clock Ratio.....................: x9.0
CPU N/2 ratio.........................: Disabled
Target CPU Clock.................: 4,597 MHz