唔好俾個數字昆到你.
975X 唔系designed for C2D, it was released before C2D. Some old 975 board does not support c2d without upgrading the Bios.
965 is optimised and designed for C2D, and it use new 南橋 ICH8 while the 975X use the old ICH7.
The performance of 975 is faster than 965 (but just very little).
975X has dual PCI express x16.