I am having the same problems with my board, however i am running an AMD. So far i havent been able to figure out why it is happening either. I have attempted to change the memory timings to those that are specified on the memory manufacturers website to no avail. It freezes just the same. It seems to me that the gigabyte boards suffer from poor overclocking abilities and memory issues. I have also made sure that I ahve the most up to date bios version. If i can find any more info ill post it here.
Update: I am having PSU issues now. i am going to try a new power supply tonight. I am also having video card artifacting and freezing. Both fans have died in my PSU. Its time for a new one. heres the one im getting.
I am also thinking this is related to my memory issue due to lack of the correct voltage getting to the memory. Guess we will see.