Today I am going to talk about the AMD GPU die height and why you might need a shim, with certain AMD cards like the 7970, 7950, and the 290x. What you are looking for is a recessed GPU die and this is what I am talking about.
Anytime you see this, Where the GPU processor is encased, you will need to use this EK shim. http://www.frozencpu.com/products/14971/ex-blc-1051/EK-VGA_Supreme_HF_HD7970_Cu_Adapter.html The reason why this is needed is because the cooler plate for any AIO unit, will not touch the GPU processor. That is a must in order to properly cool down the GPU.