Well... I was tweaking around with benchmarks and over clocking and such, and before I even started I was completely puzzled that it seems, the GT 640M in my iMac has a Memory Bus Width of 64-Bit. I Find this very weird since NVIDIA Says it only comes in 128-Bit, which I would highly prefer over this. It completely crushed this GPU.. Can someone confirm theirs is 64-Bit Bus Width also? I have checked google and everything and every one of the 640m's I see is 128-bit. even the LE edition.. This is mind boggling to me, if this really is a 64-bit gnu then apple really really screwed us base line iMac owners over.. I checked mine In GPU-Z on Windows and CUDA-Z on OSX and both say its 64-Bit.. Bummer. ** The CUDA-Z Info Is my iMac - The GPU-Z Info is a Regular GT 640M.