u can also check if the heatsink is properly seated , i once kicked my pentium 3 for being slow and it didnt want to POST after. i opened it up and found out that the heatsink was hanging on one of the side clips. fixed it tho
if still no luck if i were u i'd start from baredone, ground urself first
if still no luck if i were u i'd start from baredone, ground urself first