It says I should use 5-5-5-18... But what does that represent?
* DRAM CAS# Latency =5
* DRAM RAS# to CAS Latency =5
* DRAM RAS# preckage =5
* DRAM RAS# Activate to prec =18
The BIOS should automatically use CL5 timings. You should not need to adjust the timings manually.
What do I have for FSB/Mem Ratio?
For DDR2-800 (=PC2-6400) set FSB/DRAM Ratio to 1:1.5 [for FSB = 266 MHz]:266 MHz x 1.5 ~ 400 MHz (=DDR2-800 effectively)
The BIOS should automatically adjust the FSB/DRAM Ratio based on the SPD Profiles of your memory sticks.
What should I enter in Adjust PCI-E Frequency? (i think it's 100 default)
Why would you want to change the PCI-E Frequency? Yes, 100 is the default value. Unless you have a specific reason for changing the default PCI-Express frequency, leave it as it is.
I'm forced to run my Q6600 2.4 Ghz processor in 1.6 Ghz
Why are you forced to do that? What problems do you have?
What PSU are you using? Please provide full PSU Specs.