is CUDA SDK Toolkit really required?

[penguinkeeper]

Not necessary, hence it not blocking you and is just a warning. Due to OpenCL locking Hashcat to 1/4 VRAM, it can be helpful to give Hashcat access to all of your VRAM, hence - `7488/8191 MB (2047 MB allocatable)` . There are very few kernels that use CUDA-specific code and is usually margin of error between the two platforms