1) Why is it at 500 MHz? Isn't 400 MHz the maximum for DDR2-800, or is this the effective clock? Even if so, shouldn't it be at 800, not 500?
Ok, I am not sure how much you understand about ram so if this seems basic then you are right. Since you are running at 333 fsb but your ram is at 500. That means that you have a divider set, which I believe is defaulted to on for for most mobos now. Since this is the number CPU-Z is reporting this is not the effective speed the ram is running at. Since we are talking about DDR (double data rate) you need to double the fsb speed to get the effective speed the ram is at, which would be 1000mhz, a fairly decent OC. I am not sure what your mobo bios will call it but look for a setting that has 1/1, 2/3, 5/8, and similar and set that to 1/1. Then you will have a 1:1 ratio and an effective mem speed of 666mhz.
2) Assuming I get the RAM speed worked out, would it be better to underclock the RAM to 667 to run it in sync with the Q6600 @ 333x9, or would it be better to overclock the CPU to 400x8 (no way am I hitting 400x9 on a Freezer 7 Pro) and have the RAM at stock speeds? This is purely in terms of stability, not performance, since I imagine the performance difference between the two is negligible.
Well 333x9=3.0ghz vs. 400x8=3.2ghz so, you will see improvements regardless of ram speed. Personally I would rather use a 9 multi since it will be easier on on your northbridge. Ram speed doesn't make a drastic difference with C2D or C2Q in terms of performance unless you are doing something really ram intensive (not gaming).