i think he glued it to heatsink.
and for ur info Ponmayilal
a normal 80mm fan consumes max of 4~5W. There are ones with ultra high speeds but normal ones just so light on power consumption.
But the main ploblem will be the noise. The original GPU fan adjusts speed according to the temps, but now ull have to live with the noise[though not much irritating]
[i have a total of additional 4 80mm fans to cool my oced GFX card.]