As an experiment I set the ram skew to auto for both channels in bios.
I tried to reboot but the computer would not boot directly out of bios (my motherboard does this everytime I change a key setting like ram or fsb's etc), so I had to hold the power switch in for 5 seconds.
Upon immediatley powering up after holding in the power switch, the system rebooted with my overclock, without posting the overclock failed screen (this is also normal).
So just to see what had happened to the ram skew, I re-entered bios, and it had auto set to 150 and 100 (I think), I then rebooted (had to hold in power switch again!) and entered windows.
Tried to load BF2 and all I got was a black screen with my computer trying to re-enter into windows, the graphics cards fans were ramping up and down. I hit ctrl alt and del, and managed to close the application.
So I restarted and entered bios, changed back to manual dos skew of 750 and 600 (same old bios non boot method). Re-enter windows, BF2 does not work again (this has happened before), so at present I am re-installing BF2. Also it may have corrupted the ati drivers, I have not nailed down which one of the 2 it corrupts, but it is fixable by uninstalling ad reinstalling (what a pain!).
Bottom line there is a good chance people that overclock will run into problems in certain games, if they don't manage to find a manual workable ram skew.