graphics issue and fuse trip out

i need some help please, for a while now when i press the switch at the wall socket the pc makes a kind of "popping electric noise" for a split second but i've just been ignoring it, so a few days ago i took the graphics card out of the motherboard to clean it of dust, i unscrewed the plastic cover and vacuumed the heatsink then re assembled it and put it back in the desktop, then i tried a video game and it restarted the computer...i tried a less graphically intensive video game and it was fine, but the next day it started to shutdown when windows was starting up and bluescreens of death. so i left the pc for a few days and today i turned it on and it shutdown immediately followed by a horrible electrical smell and it popped a fuse in the fuse box downstairs. The motherboard and cpu is about 6 years old, but the graphics card is only about 3 years and the PSU is a good one from corsair.

EDIT, there is no power going to the motherboard (no green light) and it wont turn on.

MY RIG

INTEL CORE 2 DUO E6750
ASUS P5NE SLI
PALIT GTX 460 768MB
4GB CRUCIAL RAM
CORSAIR HX620 MODULAR
OCZ SSD 120GB
WINDOWS 7 64BIT