I have a question : I bought a GPU mining rig recently, which I will probably receive before Friday, and I'd like to add something like at least  8 To of HDD if possible.

Two questions come in my mind : what kind of return could I get from this and what load would it put on the CPU ? Is there a profit calculator out there ?

Since this is intended to mine GPU altcoins, it will be something really cheap, like a Celeron G1820. Do you think it will be able to handle the mining of the GPUs and of the HDDs ?

How many HDD so you think I can put on my motherboard (an ASRock Pro BTC) ?

I know that it is a lot of question, but I need it to be solved if you want that I join the community for real !