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P5Q Pro + Twin 2x4096 - 8500C5D G


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Having it seems a common issue with this motherboard and memory mix, and that's -- how to get these 2x2048MB sticks to run at 1066Mhz?


Currently they read at the defaults of 5-5-5-18, when it's rated at 5-5-5-15 T2.


Read this memory is really DDR2-800 that needs to be overclocked to 1066Mhz, but don't want to ruin my whole system with "borrowing" someone's else's config.


So what are the timings do I need to get these at 1066Mhz with my system (the QVL shows it at 1066Mhz and why I got them)? Have the latest BIOS (1613) from Asus, and still it looks like I have to manually tune them.


CPU-Z lists:


Type: DD2

Size: 4096 Bytes

Channels: Dual

DC Mode: Symmantric


DRAM Frequency: 534.3 Mhz

FSB: DRAM: 5:8

CAS# Latency (CL): 5.0 Clocks

RAS# to CAS# Delay (tRCD): 5.0 Clocks

RAS# Precharge (tRP): 5.0 Clocks

Cycle Time (tRAS): 18 Clocks


Command Time (CR): 2T

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JEDEC is the standard for DDR2. Most machines are sold as OEM and as such have a Plug and Play BIOS that does not allow for changes. No voltage chances, timings changes, etc. The JEDEC standards allow the systems to set the speed of the memory to the timings and voltages. These values are programmed into the SPD as standard values.


Then you have Enthusiast hardware that goes faster and farther than JEDEC. The highest JEDEC standard for DDR3 is 1066Mhz with 7-7-7-20 2T @ 1.8v and any bandwidth values higher, or latencies lower do not follow compliance with these standards. That is why they are known as Enthusiast memories.


Install the DRAM into the yellow slots.

Download Memtest86+ V2.11 from--->

and extract the ISO image. Burn the ISO image to an CD-ROM disk.

Download CPU-z from

Set one stick in slot 1 (Closest to the CPU) and one stick in slot 3 (Yellow Slots) enter BIOS, load setup defaults, save setup defaults and set to these values.


Enter your BIOS and set to these values:

AI Overclock Tweaker

[b]Configure System Performance Settings

Ai Overclock Tuner = Manual
CPU Ratio Setting = 9.5
FSB Frequency = 333
PCI-E Frequency = 100
FSB Strap to Northbridge = 333

DRAM Timing Control = Manual

DRAM Frequency = DDR2-1066
DRAM Command Rate = 2N
DRAM Timing Control = Manual
CAS# Latency =  5
RAS# to CAS# Delay = 5
RAS# PRE Time = 5
RAS# ACT Time = 15
Row Refresh Cycle Time (tRFC) = 60 
Command Rate = 2T (2N)
All Else to Auto

DRAM Static Read Control = Auto
DRAM Read Training = Auto
Mem. OC Charger = Auto
AI Transaction Booster = Disabled
CPU Voltage = Auto
CPU PLL Voltage = Auto
FSB Termination Voltage = Auto
DRAM Voltage = 2.1v
NB Voltage = 1.25v
SB Voltage = Auto
PCI-E SATA Voltage = Auto

Loadline Calibration = Enabled
CPU Spread Spectrum = Disabled
PCIE Spread Spectrum = Disabled
Clock Over-Charging Voltage = Auto
CPU GTL Voltage Reference = Auto
NB GTL Voltage Reference = Auto

Legacy USB = Disabled

Run Memtest for two full passes. If stable, Enter Windows, run CPU-z and post screenshots of the CPU-z's CPU, Memory and SPD tabs.



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