You have to provide us more information, it's not clear what you want to do
But CPU and GPU are two different things, you can mine with both, but with different miners
For example, you can mine in the same rig or pc: Monero in the CPU, and Ethereum in GPU, or even better, you can use Nicehash:
https://www.nicehash.com/download-centerWith nicehash you can mine with both and it's very easy to start
750ti is very weak to mine, with 1050ti you can mine something, but it's weak too
Check this website:
https://whattomine.com/coinsYou can put how much you pay for electricity and see how much each card can earn