The "Performance Enhance" setting that controls memory settings does not function yet on the DDR2 P35-DQ6 using the F4 BIOS. I have set it to Standard, Turbo, and Extreme settings but Mbench and Memset results/settings are identical between all three of them. Have you noticed this with the F5G BIOS you used?

This board should have a great deal of hidden potential left in it with this setting is fixed and a good bit of BIOS fine-tuning done I think.