If you own a ASUS P5WD-H Deluxe mobo and want to get the newer Intel E6750 (2.66Ghz) working with your DDR-800 memory (in my case some TWINX4096-6400C5‘s) you may find that when booting you get random clock speeds when posting, ranging from 2.12Ghz to 1.64Ghz and occasionally, if the Sun is aligning properly report a 2.66Ghz clock (the default).
If you want to make the most of your memory and CPU, you have no option but to overclock your FSB (obviously I’m not responsible if you fry anything). Firstly its important to ensure that you have correctly installed the CPU and make sure you have the latest BIOS from ASUS - right now, the latest is BIOS 2801 released in August 2008.
In the BIOS, goto the ‘JumperFree Configuration’ and make sure that ‘AI Overclocking’ is set to Manual. Then set the ‘CPU Frequency’ as 400 (default multiplier for Intel E6750 is 8 which means 8 x 400FSB= 3200Mhz Clock), then select your ‘DRAM Frequency’ to DDR2-800. Leave everything else as Auto.
NOTE: You may want to disable HyperPath 3 if you notice that MemTest is failing. To do this goto the ‘Chipset’ configuration item under ‘Advanced’.
Save and restart, press {TAB} to get the boot screen, you should see 2.66Ghz and memory running at PC6400. Next thing to do is to get MemTest and let it run for atleast one pass. My setup is rock solid at DDR800, CAS 5-2-2-18 with the E6750 @ 3.2Ghz.
Alternatively, if you dont want a higher clock, stick to the standard 2.66Ghz and sacrifice your RAM speed, you should go a different route:
- AI Overclocking: Overclock Profile
- FSB1333/DRAM-667 or FSB1333/DRAM-834 (memory runs at 416)
- Everything else Auto
Better instructions to make it easier to understand.
Leave everything not specified as Auto. You may want to disable Hyperpath3 if you find that Memtest fails.
Configure for 2.66Ghz and PC5300 (DDR-667)
Configure System Frequency/Voltage
- AI Overclocking = Manual
- CPU Frequency = 333
- DRAM Frequency = 667MHz
- PCI Express Frequency = 100
- PCI Clock Synchronization Mode = 33.33
- Memory Voltage = 1.9v
- MCH Chipset Voltage = 1.65v
Advanced Chipset Settings
- Configure DRAM by SPD = Disabled
- DRAM CAS# Latency = 5
- DRAM RAS# Pre-charge = 5
- DRAM RAS# to CAS# Delay = 5
- DRAM RAS# Activate to Pre-charge: 15
- DRAM Write recovery Time = 6
Configure for 3.2Ghz and PC6400 (DDR-800)
Configure System Frequency/Voltage
- AI Overclocking = Manual
- CPU Frequency = 400
- DRAM Frequency = 800MHz
- PCI Express Frequency = 100
- PCI Clock Synchronization Mode = 33.33
- Memory Voltage = 1.9v
- MCH Chipset Voltage = 1.65v
Advanced Chipset Settings
- Configure DRAM by SPD = Disabled
- DRAM CAS# Latency = 5
- DRAM RAS# Pre-charge = 5
- DRAM RAS# to CAS# Delay = 5
- DRAM RAS# Activate to Pre-charge: 15
- DRAM Write recovery Time = 6
MemTest it again to ensure things are rock solid. As this is for the Zeus rebuild, I’ve opted for the non-overclocked option 
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