What util do you use to measure the temperatures?
I have GA-965P-DS3 and when I changed the BIOS(F10 to F11), the EasyTune5 utility started to show temperatures of both the CPU and the northbridge higher for about 7'C. The BIOS is also showing higher temperatures, but I am sure the temperatures are the same as with the F10.
Try SpeedFan or CoreTemp.

BTW, I've ordered a P35-DS4 and it will arrive for about 10 days.
I want to know, what settings and voltages have you used to achieve 475MHz FSB?