Just remember.. For folding you only need the Shader Strap's overclocked. The Core and Memory overclocks only lead to more heat and possible instability.
There are times where the shader's won't go any higher without core but you take a chance of an unstable machine error on the GPU2 clients.
Shader straps go up in 54Mhz increments I believe so use that as a guide and get shaders as high as you can without core/mem increases.
That's just for folding now, regular gaming and OC then all 3 are pertinent