Let me clear : there are two x4 955 , one is x4 955 Black edition - 125w and another Asian version x4 955 (non black edition) (OEM only) - 95w
see the difference Compare AMD Phenom II X4 955 (125W, rev. C2, BE) / Phenom II X4 955 (95W, rev. C3, non-BE)
Gigabyte GA-78LMT-S2PT supports only upto 95w cpu. you need atLeast ASUS M5A78L-M LX V2