How to Install an Aftermarket GPU Cooler: Very Carefully

An aftermarket GPU cooler is exceedingly complicated to install, and you run the risk of bricking your card if you do it wrong. Here’s the gist: You unscrew the stock heatsink on the card via the super-tiny screws on the underside of the card. Take care not to bend or otherwise grip your card too tightly and, for the love of all things holy, be gentle—but forceful—when removing the tiny screws.

Note the sheer size difference between the card’s
stock heatsink (far left) and our aftermarket cooler
on the right. Goodbye, noise!

You’ll have to clean off the GPU (rubbing alcohol works great) and likely apply more thermal paste to it and to any of the other raised components that touch your new heatsink. You’ll also have a complicated series of
washers, standoffs, and screws to fiddle with as you mount your new cooler in place—this varies based on the aftermarket cooler you’re using. No matter what, be careful: A videocard is a delicate object. Snap off or otherwise bump the wrong electronic element, and you’ll find yourself with a $300 coaster… or worse.

Taking a videocard down to its raw components—a circuit board and
chip, in this case—is an extremely delicate process.
You can easily brick a PC part. 

quote from : here