Dell Studio 1558 i7 overheating RAMINFOTECH LAPTOP SERVICE CENTER

Dell Studio 1558 i7 overheating

My laptop freezes after an hour or two of working with TeamViewer, and I think this is because of the overheating problem.

What would be better - to add copper shims (in the places where i drew red circles: gpu ram, gpu chip, south bridge heatsink) or to stick with thermal pads that were there originally.
Here is a picture with the heatsink and cooler removed -

http://www.raminfotech.netIf going with the copper shims: which sizeswould be best?If it the shims would be too wide, they mighttouch the metal pins near the gpu chip.Is there a preferable thickness, while takinginto account the step of the cooler, - see bellow -, and heat conductivity?The cooler is not flat at it's bottom, it hasa step (about 0.5mm high) dividing video ram and the gpu unit.