So i removed the logic board the other night from the macbook to inspect a charging issue. Put it all back together. This is a C2D 2.1ghz, 1gb ram, 160gb hdd, Mid 2007 model. Just last night i did an update as i installed a fresh copy of leopard on the machine and then all of a sudden this Crackling sound starting coming out from the top left corner.. It appears to be where the speaker is.. and right above where the fan is for the CPU. Now the logic board stayed out of the machine for a few days and when i put it back on.. i did not put any new thermal paste back on the cpu dyes.. Should i have? Now the macbook starts up.. makes the crackling sound.. and it just sits at the Apple logo and seems to boot forever never finishing the boot.. Anyone have ideas? Is it perhaps that i should have applied new thermal paste and the thing is now overheating?