Okay, Im going to admit. At first, this idea seems a bit farfetched and probably completely unneeded. Therefore, Im going to go ahead and explain a bit of background of this idea and whether or not you agree is completely up to you. The copper mod was first heard about with the old Dell Inspiron 8500 and 8600 notebook PCs. During those laptops, the high end video card option was the ATi Radeon Mobility 9600 Pro Turbo, a fairly powerful midrange video card of its time. The Inspiron 8500 was Pentium 4 Mobile based while the 8600 was based off the Centrino chipset with a Pentium M processor (one of the early generation chips). The ATi Radeon Mobility 9600 Pro Turbo was a powerful card, because of it, a lot of heat was generated and it was fairly common for this card to overheat and shut down the entire computer. The problem was discovered that the heatsink designed for the ATi Radeon Mobility 9600 Pro Turbo was the same as for the slower, less heat generating cards such as the nVidia GeForce FX5200. The heatsink itself however isnt a flaw of the design, its the heat transfer. The heat generated by the diode and ram chips were carried to the heatsink by a very inferior thermal pad of a few millimeter thick layer. Because of this, using a thin layer of thermal paste was out of the question since it would never touch the heatsink in the first place. Therefore, a copper plate was introduced to bridge that gap. This introduction of copper to an aluminum stock heatsink resulted in close to 20+ deg C heat reduction on several accounts. Now, while the MacBook Airs heatsink does touch the diode, the heat transfer is still inferior due to its size. Heres how the MacBook Airs heatsink gets rid of the heat created by the diodes. The heatsink, which is essentially a plate of aluminum for the Rev B and Rev C or a heat shield wrapped in aluminum foil for Rev A, draws the heat from the diode and heats up the entire plate. The plate is cooled by a small fan that creates an air flow. This flow is basically sweeping the heat on the plate out the vents in the back. Aluminum is a great heat radiator, meaning it is great at getting rid of heat fast. However, its not the best conductor, which draws the heat from the source. Now heat is energy and the aluminum plating can only carry so much heat before it is full. The heat generated under full load from either the CPU or GPU can easily exceed what the aluminum plate can handle very quickly. The copper mod is designed to bridge a gap in which heat can be conducted faster from the source, but still allow enough time for the radiator to radiate the heat away. This is done in which the copper is placed between the Diode and Heatsink. The dense mass of the copper is allowed to store more heat while still allowing the radiator to radiate the heat quickly. So why not build a heatsink completely from copper? Theres several reasons for that, one is that copper is a terrible radiator. Copper loves to store heat, not radiate it out. Aluminum however hates to store heat. It loves to radiate heat as fast as possible but due to its lightweight and low mass it cannot store that much heat before its full. Look at it from all the other heatsinks, even the ones designed in the MacBook/MacBook Pros. The base, in which touches the diode are almost always copper. However, the fins at the end of the base are usually a combination of Copper and Aluminum. This is what Ive done with my MacBook Air, pictures attached. I applied a thin layer of thermal paste on the diode, then placed a thin piece of copper on top of it. From there, I applied a thin layer of thermal paste on the heatsink and squished the copper in between. This combination allows the copper (conductor) to effectively draw heat from the source (diode), and still allow the aluminum (radiator) to radiate heat away. Under 100% load testing (Folding@home and nothing else), the fans have stayed ~4500-4800 RPM with temps ranging around 70-78 deg C However when surfing the net with Folding@home, the fans will rev back up to 6200RPM. But even with the fans revving to 6200RPM quickly, it is delayed longer than stock and the fans return back to 2500RPM quicker.