Normally speaking, Intel 945GZ chipset does not support processor with Front Side Bus above 800MT/s. But some mainboard manufacturers broke that limitation. Please refer to GIGABYTE TECHNOLOGY Socket 775 - Intel 945GZ - GA-945GZM-S2 (rev. 6.6), make sure the PCB version of your mainboard is rev. 6.6 and update your BIOS from F1 to F2 to enable it to work well. Failures in updating BIOS might damage your system, so everything is at your own risk.
If your mainboard has a PCB version of 2.1 or 3.x, this processor, Core 2 Duo E6700, is working under FSB at 800MT/s, so nothing could solve your problem, except overclock the FSB of your mainboard, and that would make your system work unstably. In other words, in this situation E6700 is not supported by your mainboard. So please do not waste your time.
Hello Aaron thank you so much for the answer. My PCB version is 3x so it's better to put back on the 4400.
Again thank you
Well, please do not get me wrong, I would never love to show off my knowledge. All the information is obtained from websites. I just found those questions interesting and answered them for killing time. And that's all.