Hardware suggest
I'm planning to use my Mac for password cracking it has a GT750M-1GB GPU and CPU of Core i5 2.9(haswell).
I know using hashcat against oclhashcat for brute-force method is not good practice... so the answer i need to know is about "GT750M-1GB GPU", Does it perform well or i need to use a better GPU?

note: the password i need to crack has 69 length
mac/OS X is only supported by cpu hashcat ( https://hashcat.net/hashcat/ ), windows/linux instead are supported by all cats (cpu hashcat, cudaHashcat, oclHashcat).

Yes, the GPU may be faster than your cpu (given you are able to install a - proper/supported - operating system)

Cracking on laptops is not recommended, the heat etc may be a very important problem.

Cracking a password of length 69 is not supported, the limit for cpu hashcat/oclHashcat is 55 (and for some attack modes even less). Anyway, even if that limit wouldn't exist, cracking a password with length 69 is impossible, if the password is not very, very, very easy, or most of the characters of the password are known