No, because the Fermi ALUs can't accept 40-bit wide data - they can accept *either* 32-bit FP or 32-bit int. There's no benefit to supporting a strange FP40 format, since it's not standard and no one could use it, neither under DX11 or OpenCL (or even CUDA).
The Fermi ALUs can accept 32-bit wide datatypes, either 32-bit integers or 32-bit FP. The details of how they've been implemented internally are likely much more complicated than just saying they have a "binary capacity of 40 bits", given that the ALUs are ganged up to operate on larger data types (like FP64).