I am completely stuck at 3.6 with my Q6600 G0. My load temps were around 65C with all 4 cores stressed at 3.6ghz and 1.55vcore. I have all my voltages except for vdimm in hopes that I would be able to hit anything above 3.6. Nothing above 400x9 or 450x8 is stable even though the board can hit 490 with a 6 multiplier. Am I missing something, is it my temps, or am just limited to 3.6?
Need to see your bios settings.

Here's one of my previous bios settings for 3.8 ghz on the Quad. One of the key settings here is CPU PLL. Before upping this to 1.6, I had stability problems at 3.7+. Now it will run up to 4.1ghz. Note north bridge and fsb voltages can be kept pretty much at their lowest values through out.

Code:
JumperFree Configuration Settings
AI Overclocking: Manual
CPU Ratio Control: Manual
- Ratio CMOS Setting: 9
FSB Strap to Northbridge: 333
FSB Frequency: 422
PCI-E Frequency: 100
DRAM Frequency: DDR2 844
DRAM Command Rate: 2T
DRAM Timing Control: Manual
CAS# Latency: 4
RAS# to CAS# Delay: 4
RAS# Precharge: 4
RAS# Activate to Precharge: 12
TWR: AUTO
TRFC: 42
TWTR: AUTO
TRRD: AUTO
TRTP: 6
DRAM Static Read Control: Enabled

Transaction Booster: Disabled
Relax [0]
Clock Over-Charging Mode: AUTO

CPU Spread Spectrum: Disabled
PCIE Spread Spectrum: Disabled

CPU Voltage: 1.475v (1.47 in OS vdroop to 1.46v) Pencil Modded
CPU Voltage Reference: x0.63
CPU Voltage Damper: Enabled
CPU PLL Voltage: 1.60
DRAM Voltage: 2.20
FSB Termination Voltage: 1.20
North Bridge Voltage: 1.25
North Bridge Voltage Reference: x0.67
South Bridge Voltage: 1.05

Advance CPU Settings
CPU Ratio Control: Manual
- Ratio CMOS Setting: 9
C1E Suppport: Disabled
Max CPUID Value Limit: Disabled
Vanderpool Technology: Disabled
CPU TM Function: Disabled
Execute Disable Bit: Enabled
PECI: Disabled

USB Configuration
USB Functions: Enabled
Legacy USB Support: Disabled
RLM