What is your RAM multiplier set at? If your running at a FSB of 416 with DDR2 800 you're gonna want the ram multiplier to be at 2, running at a 1 : 1 ratio.
If you run CPU-Z with your current 2911mhz (7x416) overclock check how much the RAM is being overclocked as well. If its pushing over 1000mhz, you'll prob want to lower the ram multiplier in the BIOS.
If I'm talking out my ***, feel free to slap me
I just remember having to do this when I was overclocking my system, as I was pushing the RAM too far and making my system unstable.